Christopher Fisher I think that there are many more reasons accepting the fact that they died. L, personally, do not see more than one reason or two reasons why they could have lived. There is also stronger indication of them dying. I think that starvation and hypothermia are two strong reasons why they die. The other reason why they die does not have as good of substantiation, but it is better than some of the reasons why he would have lived. One reason why Jason and Gabriel died is because of starvation.
It says in chapter 22 of the book that they were trying to catch fish, but had only caught two sis after countless tries. It continues to say that at night he was tortured by hunger. The book also says "He [Jonas] was newly aware that Gabrielle safety depended entirely upon his own continued strength. " Thus if Jonas died then Gabriel would also die. Jonas started to feed' memories of food to Gabriel and himself, but afterwards there was only pain from hunger and starvation. In the last sentence of the book, Jonas thinks he hears music or an echo.
I think that this resembles him dying because his hearing fails more or less and with him dying Gave also dies. Another reason why Jason and Gabriel die is because of possible hypothermia. In the last part of the book, it says the extreme cold that Jason felt as he tried to climb to the top of the hill. He had little clothing. The only clothing that he had is a tunic, trousers, socks and shoes and the only clothing that Gabriel had is a blanket and possibly a diaper. Near the end of the book it says that his feet were numb.
This would imply that he and Gabriel are at least frost nipped on their fingers and toes. Jonas is giving what little memories of warmth he has to Gabriel and himself. Although this helps, it is only mental and does not help the physical stated of his roost bitten toes and fingers. While riding down the hill on a sled he gets much colder. I think that at the end of the book when he struggles to keep his consciousness, he loses it when he debates hearing music or an echo and possibly dies of hypothermia.
The last reason I think that Gabriel and Jonas die is from Jonas hallucinating. With Jonas giving memories to him and Gabriel, he might have lost track of reality. The sled might not have been there. The houses and lights could merely be a remnant of his memories of family and Christmas time from chapter sixteen. These houses could tie possibly be large trees and much closer. The sled could be a rock that he imagines moving.
Then from all this he would die from the reasons I listed above because he never made it to the 'house'. All in all I see much more evidence in favor of Jonas and Gabriel dying at the end of the book than I see of them living. Most of my points have very stable evidence. I do not think that all of the essays showing how they live will have as much confirmation. It is sad that they died, but not all stories are happy. Not everyone has a happy ending, even Jonas and Gabriel.