I just recently saw a meme which implied this idea to be true, even in the comments I saw one talking about how this person's history teacher told their class about this being true.
I personally didn't find any evidence of this being certain. Everything I found on "Leonardo Da Vinci's boyfriend" was about Cesare Borgia, but no accounts of him and Leo dating, only speculation. Furthermore, on "The face of Jesus" was also mentioned Gian Giacomo Caprotti, who was a pupil of Leo's. Both of them seem to be "the face of Jesus" but none are proven to have dated Leonardo.
I'm sorry if this is a dumb question, but curiosity struck me and maybe here I will find my answers. I also apologize for any misspelling, bad grammar or poor formulation, English is not my mother tongue.
I can recommend some earlier answers for you on this topic. Leonardo's sexuality is discussed here by u/mimicofmodes (thanks for reposting this recently, which helped me find it!) and more briefly here by u/butforevernow.
I know not who modelled Leonardo's Jesus, but you can read u/Spencer_A_McDaniel's blogpost here and u/sunagainstgold's answer here, on how the portrayal of Jesus has changed throughout history. Hopefully someone more knowledgeable on Renaissance art history could help out here