Does very high PSA when diagnosed predict long term outcomes?

I can't really give an answer, but my husband got diagnosed 1.5yrs ago and his PSA was almost 300 and PSMA scan revealed it's all over his body! after ADT since then (Firmagon monthly injections and Zytiga pills) plus chemo, scans show a LOT less and he looks fine and acts fine, they are saying he's doing extremely well!
He's 56 and exercises every day- weight lifting and treadmill and eats pretty perfectly!
At diagnosis, the stats said 30% make it 5 years in his situation, so we'll see!