Lot depends on age
His age at diagnosis, general health, will to live, strength to fight this beast, receiving compassionate care, having loving support system, all are factors that help get to the answer. Even then, a knowledgable, experienced doc does would not try to give a specific answer. .
If he is under 65, it is usually a more aggressive cancer
(my father died at 55 with it); if over 75, may have yrs left.