Unless he uses his stand to kill himself, does not have or use a protective ability, or the stand is lacking in speed and precision, his stand will most likely allow him to survive. As we can see in JoJotaro's first scene in Jonjoseph's Bazinga Adventures: Act III - Standdust Crusaders where he is in the prison cell, his stand, Standstar Platinum, catches the bullet when Jojotaro tries to shoot himself
Edit; garmmer r 🅱eter