If the Nazis had gotten the A-bomb, would the Allies have capitulated?

No, there would be no capitulation on the Allied Side, and Great Britain would have been severely annihilated but not wiped out. The Russians would continue fighting to the death and America since it is far away would never surrender and would hasten also their A-bombs production and could ultimately catch up with the Nazis. It would be a more deadly war, but just the same, the Allies would win. Wish you luck.