There is so proof he is alive though.
There might not be proof, but there are many indications he was far from being dead
1. There were many elite ninjas like him took the shot which ems sasuke and base naruto blocked neg diff. Well the fire ball actually aimed at sasuke closed range, not that "dead guy" we are talking about
2. No one get killed by a fireball neg diff in whole series
3. Onion share same situation except getting fired at closed range and still alive. Of course he lied on the ground like a corpse like you said
So to say the guy is dead is too far fetch