I think the poor guy is a walker by now. Tyresse may have survived a similar situation, but Kenny is no linebacker, and didn't even have a functional weapon with him (Tyresse had his hammer he used since the outbreak).
Maybe he shot himself if you save some bullets for him when he tries to save Ben. Christa does mention "I heard a couple shots" if you do that. I still say he's a walker. Most likely one of the pitiful ones that has almost nothing left on it because so many walkers ate it all. Just a head, organless torso and an arm or something like that.