I am thinking, for instance, of David Bowie's Young Americans album, which has clearly funk/soul influences. My question then would be, what soul/funk musicians influenced Bowie during the 70s, and in particular, what musicians were an inspiration to Bowie to make the Young Americans album?
Most of the Young Americans sessions, which began on August 11, 1974, were at Sigma Sounds Studios in Philadelphia, where the producer/songwriter team of Kenny Gamble and Leon Huff recorded the likes of The O'Jays, Harold Melvin & The Blue Notes, and Billy Paul, among others, on their Philadelphia International Records label. In addition, famed Philly producer and arranger Thom Bell produced other well-known soul artists, like The Spinners (formerly of Motown), The Stylistics, and Dionne Warwick there. I'd be inclined to say that Young Americans is very influenced by Philly Soul (and previously mentioned artists) for that reason.
The musicians and producers Bowie pulled in for the Young Americans sessions at Sigma Sounds Studios in Philly could also hint at his influences.
Producer Tony Visconti
Tony Visconti had worked with Bowie before (and has worked with him a bunch more since), and before Young Americans, most of his production work had been for rock music, specifically prog rock and glam rock; producing the pioneering prog rock band Gentle Giant and the famous glam rock band T. Rex. In terms of soul and funk music, it seems as though Young Americans was Visconti's first foray in that area.
Producer Harry Maslin
Young Americans was one of, if not the first producer credit for Harry Maslin, but he had worked as an engineer for a number soul/funk albums in the early to mid 1970s, for artists like Mandrill, Young Holt Unlimited, The Persuaders, and Pacific Gas & Electric.
Guitarist Carlos Alomar
At that point in his career, the 30-year Bowie collaborator Carlos Alomar had never heard of Bowie before, and upon meeting him recalled that he was "the whitest man I've ever seen - translucent white". That was a bit of an aside. Anyway, in the 60s, Alomar played in the Apollo Theater house band, and apparently toured with James Brown for eight or so months, though I'm unable to find any James Brown recordings on which he appeared. He later backed up the likes of Ben E. King and Joe Simon in the studio.
Keyboardist Mike Garson
Garson had worked with Bowie before, on Aladdin Sane and Diamond Dogs; his influences were mostly Jazz.
Saxophonist David Sanborn
David Sanborn, even by August 1974, was already a prolific session musician, having recorded with James Brown (appearing on Brown's hits "Funky President (People It's Bad)" and "My Thang", among others), Stevie Wonder (appearing on "Tuesday Heartbreak" from Talking Book), and a slew of jazz musicians, including Gil Evans and Hubert Laws. Fun fact, David Sanborn didn't appear on "Fame" on Young Americans (more on "Fame" below), but he did appeared on James Brown's "Hot (I Need To Be Loved, Loved, Loved)", which was essentially a rip-off of "Fame" that James Brown apparently recorded due to his increasing irritation of white artists putting out funk songs similar to his. The guitar riff says it all.
Bass Guitarist Willie Weeks
Another prolific session musician, bass player Willie Weeks had already played with most notably Donny Hathaway, appearing on his Live album in 1972. He also played on Stevie Wonder's Talking Book, specifically the track "He's Misstra Know-It-All" and Aretha Franklin's Let Me In Your Life. He also recorded with a variety of non-soul and non-funk artists, including George Harrison, guitarist Ron Wood, and jazz musician Herbie Mann before recording with Bowie for Young Americans.
Drummer Andy Newmark
Still another prolific session musician, Andy Newmark had most notably been a member of Sly & The Family Stone for two years and recording on the band's album Fresh before hooking up with Bowie. Most of Newmark's other work, both before and after Young Americans has been more in the rock camp than in the soul or funk camps.
Percussionist Larry Washington
Larry Washington was essentially the house percussionist for Sigma Sounds; he appeared on a bunch of recordings with The Spinners and all the other artists I listed in the first paragraph. For sure, he was the sessions' biggest tie to the Philly Soul sound.
Vocalist Luther Vandross
That's right, 80s soul superstar Luther Vandross sang back up vocals on Young Americans. He certainly paid his dues in the 70s before breaking out as a solo artist with "Never Too Much" in 1981, but his resumé pre-Bowie is actually kind of short. He sang backup vocals on Roberta Flack & Donny Hathaway, a duet album by Roberta Flack and Donny Hathaway... and that's pretty much it. After Bowie, he recorded with Chic, Diana Ross, Ringo Starr, Ben E. King, and many, many others, but he was a relative newcomer when the Young Americans sessions started.
Vocalist Robin Clark
The wife of Carlos Alomar, Robin Clark sang backup vocals with Luther Vandross on a lot of the same recordings in the 70s, though obviously she didn't gain the same level of fame. Her experience pre-Bowie, however, is a bit different. She appeared on the Performance album by soul singer Esther Phillips, and a few other non-soul and non-funk albums before joining Bowie in the studio for Young Americans.
Vocalist Ava Cherry
I haven't been able to find much about Ava Cherry. She had a few solo albums in the 80s and 90s, but I can't really find anything she did before joining Bowie for Young Americans.
It should be noted that two songs on Young Americans, "Fame" and "Across The Universe", were not recorded in that stretch at Sigma Sounds; they were recorded at Electric Ladyland Studios in New York City in one day in January 1975, with John Lennon. Carlos Alomar seems to be the only holdover from above for that session.
One could deduce that the idea for recording "Across The Universe" was because John Lennon was there; as for "Fame", the story is a bit different. Apparently Carlos Alomar had worked out that riff as for a cover of "Foot Stompin'" by the 50s doo-wop group The Flairs, though in listening to the song I personally don't really hear the similarities. But it's probably safe to say the influences for "Fame" lie in The Flairs.
Hopefully this long-winded post answers your question; it's hard to pinpoint the specific artist influences without asking Bowie himself (and at that point it might be tough for him to remember what specifically he was listening to and inspired by 40 years and 15 albums ago), so I think tracing evolution of the musicians he chose to work with and looking at the studio at which he chose to record is a good way to go about trying to frame his influences at the time.