After Jonas flees the community with Gabriel in order to save him from being released, Jonas engages on an arduous journey to Elsewhere, which is far from his comfortable, safe, structured community. Jonas relies on his cold memories to avoid the heat-sensing search planes and transfers warm, peaceful memories to Gabriel when the weather becomes increasingly colder. In the final chapter of the novel, Jonas struggles to reach the top of a snowy hill, where he finds a sled. Jonas's experience comes full circle as he and Gabriel sled ride down the snowy hill towards a quaint village at the bottom. At the bottom of the hill, Jonas sees warm light emanating from the cottages and hears joyful music coming from the homes. It is implied that Jonas and Gabriel will seek refuge in the small village, where they will enjoy the Christmas celebrations and friendly environment.

This question gets asked a lot, because the book has an ambiguous ending.  Please see the link below for some answers.

Personally, I think they both die.