If Pitt is truly his number one choice, AND he’s ready to commit if the finances line up, he could contact his adcom to tell him “if there’s a way to increase my generous award of 5K to 10K I am excited to withdraw my other applications and commit to Pitt”.
Then see what happens.
If he’s NOT ready to commit, it’s going to be a long, drawn out process (or Pitt will just say “take it or leave it” of them upping the offer modestly, him asking for a “skootch” more, etc.
Agree with Thumper- Pitt will not view Temple as a peer school, so what he got from them is a “nice to know” but not serious competition.
Good luck!