[chin7an]

Asking for a raise in a tactful way is something only your friend can do, best you could do is coach him.

That said, if you think that's never happening at your employer, then they have some options IF they're here on an H-1B. IANAL & I don't know anything about other visas either.

If your friend has a degree from a reputable US school and your employer is also reputable, they should have no trouble finding a new job and transferring their visa. GC applications may be redone as well, with the caveat that you don't hit H1 renewal after your previous employer revokes their application and the new one is approved. You could help coach them for interviews and with referrals, but that's about it.

There are risks involved in all these steps of course, so weigh the current salary with potential rise.