Doug Franks, the boyfriend who Harvey had breakfast with the morning of the day he was assassinated, died from AIDS in the 80s, according to Anne Kronenberg in an article I found.
Billy Wiegardt, the "roommate-with-benefits", may very well be dead; I found a death record for a William Wiegardt who was the right age and died in 1988. Also dead among Harvey's friends are Dick Pabich (AIDS, 2000) and Jim Rivaldo (liver cancer, 2007).
Despite a lot of searching, I can't figure out what happened to Bob Tuttle, the boyfriend from L.A. If he's still alive, he's the only one left of Harvey's "major" boyfriends.
Gerard Dols is a Christian chaplain who has recently come forward to claim that he's the real "boy from Minnesota", who went unnamed in The Mayor of Castro Street and was called Paul in Milk. This is the kid who couldn't leave his homophobic parents because he was in a wheelchair, but finally managed to get on a bus and called Harvey again when he was in California to thank him. Now, Gerard Dols says, he's a "former homosexual".
Reasons why he may be a total fake:
1. He claims that Harvey wanted him to move in with him and his partner. Seeing as the partner at the time would have been Jack Lira, I'm not buying this one. Yeah, Harvey had a weak spot for cute young gay men in trouble, but how breath-takingly dumb would it be to move a cute young guy into the horrendously unstable Milk-Lira household? I'd be a lot more inclined to believe this if Gerard Dols had said that Harvey offered to help him find a place if he made it to the Castro, or if Harvey had found someone Dols could move in with.
2. He also claims that he may have been partially responsible for Jack Lira's suicide because he called Jack an hour before Jack killed himself and Jack thought he was trying to take Harvey away from him. It's possible. But it also sounds self-aggrandizing - I didn't just know Harvey Milk, I am in fact directly connected to his boyfriend's suicide! And everyone who would know if I was lying or not is dead!
3. Though the source is unnamed, a blogger is claiming that someone involved in the making of Milk told him not to concern himself too much with Dols.
4. Dols says all his gay friends abandoned him after Harvey died. Why? People don't just decide, "Hey, you know our friend Gerard, who knew that guy Harvey Milk, who just died? Let's abandon him!"
5. He says that anyone who doesn't believe him can ask Anne Kronenberg, but he spelled her name wrong.
6. All the things he says are things that either anybody could know, or the only people who could deny or confirm them are dead.
Why it's all a bit confusing:
1. Another site claims that "someone who knows more about the movie than just about anyone" (if they're telling the truth, my money's on Cleve) told them that Paul in the movie was a composite of lots of different teenagers who called Harvey. But, unless Randy Shilts got it wrong or made it up in The Mayor of Castro Street, there really was a kid in a wheelchair from Richmond, Minnesota. Where's Don Amador? Is he still alive? He's the one who temporarily housed the kid from Richmond. I found somebody named Don Amador who lives in California, but I have no idea if that's the guy. (Check the comments section on that link: someone who claims to be Gerard Dols commented a few times, and he writes like a fifth-grader.)
2. On this podcast with Concerned Women For America, he sounds as nice about Harvey as an "ex-gay" can sound, pointing out that Harvey was kind and compassionate towards him. (He also says that he's sad Harvey never had the chance to know Jesus; dude, gay thing aside, it's called "being a Jew.") There are a few points where the people interviewing him are trying to get him to be more condemning, but he's not.
On the whole, whatever the truth of the matter is, he sounds like something of an unfortunate soul. On the podcast he talks a lot about the problems in the gay community, but he attributes them to just being gay, not to the various psychological problems gay people have from being misunderstood. I think it's possible that he's the boy from Minnesota. It's also possible he's lying. If he's lying, though, he definitely did his research.