At least Riker, Picard, and LaForge. I present as evidence these two episodes of TNG.
According to some online stories I found about the show – all of them were gay. And very active, too.
Starfleet has a “don’t ask, don’t tell” policy.
Unless it was mentioned on screen I don’t really think it counts.
It’s irritating that the bisexuals all exist in the dark and immoral Mirror Universe.