"I always... hated... yellow... MOTHERRRRR!!!"
-Erwin, Pac-Man World 3
While it seems likely that he might have perished in the explosion, Erwin's true fate has never been expressly stated in any form. Not to mention the fact that villains from previous games are always never shown to have ever died following their final defeat. Generally getting themselves imprisoned, seriously roughed up, or banished.
Erwin has later been revealed to be a playable character in Pac-Man World Rally, however the canonicity of this game is debateable.
His squeaky voice and whiney attitude perhaps confirms this, it is likely that Erwin's mean spirited and bigoted nature is a result of short-man syndrome.
Erwin is a little man with a big head, yellow eyes and greyish skin. He resembles the popular Reticulan Grey style of alien often used in UFO pop culture. He has a Radio active Warning symbol on his teal Hazmat suit in reference to his radiation obsession. His back hair kinda resembles Homer Simpson. He is likely not a native of Pac-Man's home planet.