You can see the girlfriend being helped out of the car by the firemen, and she is walking on her feet. De Niro's fate is a bit ambiguous (though you can see his hand moving), but Scorsese has said in more than one place that all three of them survive, but they are essentially persona non grata in their old neighborhood.
Have to look through some other books, but here is a synopsis from Martin Scorsese: A Journey, which was done with the full participation of the director: "Michael pursues them, and a gunman (played by Scorsese) shoots up their car. Johnny Boy and Charlie survive, dazed and bloody."