That depends entirely on which round. 20mm rounds (like the Hispano) could punch through the armor "tub", through the armored seat, through the pilot, through the instruments, and keep going into the engine or other parts forward. That did happen.
Small rifle caliber rounds less likely to happen.
50Cal API? Maybe, but only a small %, IMO.
What about the tank extending below the armored "tub", and bullets passing below the cockpit and hitting it's lower area, which is exposed?