You're such a brainlet, all you ass pull retards are, lets just forget there are already a few set up explanations for his potential survival.
Ass pulls are born out of a lack of planning/set up, at some points your story will kind of write itself and maybe logically contradict what you want to happen, i.e, writing ones self into a corner, and having to make up something on the spot to get out of it.
Absolutely nothing leading up to erens 'death', logically followed to him getting his head blown off, it'd make 100x more sense if she missed, or if she hit his arm, or if she never got a shot off in the first place.
The whole scene is another case of isayama going out of his way to create a scenario, so much so that it doesn't even make much sense that it happened.
This alone tells you there's something he wants the reader to see, and that eren obviously isn't dead, if anything the "asspull" is isayama having eren get shot, just so he can show off whatever it is he wants to show off.