In my opinion I believe Jonas lives on, however many people may say all the facts line up to prove Jonas has died. This is partially just a gut feeling I have to make my statement but the book also said "Jonas felt himself losing consciousness" if somebody from the house found Jonas in time, he and Gabriel would be saved. Also, when the Giver goes "elsewhere" the community receives the memories, this was never said to happen which is the main reason I think Jonas is still alive. The ending did frustrate me though because I like straight forward endings.
I've read quite a few articles on the ending of The Giver and in most she has said simply "I left the ending up to the reader" However she does mention a book The Messenger in which she says Jonas is featured, grown up. She also said the she liked the ambiguity of the ending of The Giver but that was of course effected by the announcement of the sequel. On top of that Lois gave hints in the interviews that Gabriel and Jonas are still living.
Sorry I'm just posting this now, I thought I did last week but I guess it never went through.
