He isn't dead. Way to much foreshadowing that he is alive. From Michonne's speech to Heath to Glenn's sign off to Rick. He is alive under that dumpster.
POSSIBLE SPOILER: Beware if you scroll down to read. The biggest tell is a paparazzi pic from the set showing him interacting with a character from the comics (Jesus) that has not been introduced yet.
Love the show, just hate it when they act stupid in a survival sense, shooting unnecessarily, trying to save everyone even if injured. And I don't think Glen's dead. No way they'd give a main character that much of an...ambiguous...death.