Molluck is alive. End of story, no debate.
I would say instead of a slim chance him being alive its more like a 3/4 chance he is alive, and a slim chance of him being actually dead. So many times OWI has lead us to believe he is alive, whether it be in there entries about him, designer diaries from the original version of munch, multiple times they said things like:
"Molluck took the easy way out in dying...or did he..."
I personally think they will suprise us by making him come back much later, and make us think he is dead for now, until he returns at the end.