In my opinion, you can say that Jonas and Gabe make it out of the community and end up Elsewhere. They make it out to a real world where there are feelings and everything. You can say this because Jonas is going down the hill, in the snow (so it can't be in the community) and he sees the lights and he hears the music.
But I think you can also say that he is just making it up in his mind. Maybe he is actually dying. The place where he is going is just like the one in his memory. Why would he have a memory of a place that he is in now? The memory would have to be from long ago so the place couldn't exist in the present. He's just remembering that place as he dies.
In the book The Giver one can interpret the ending as Jonas and Gabriel as dying or Jonas and Gabriel as escaping and beginning to develop their own memories when hey hear music and see lights.
When they have escaped Gabriel is very cold. Jonas wonders if he is still able to give a memory to Gabe. He wants to give him the warmth of sunshine. He forces the last of the warmth into the thin shivering body of Gabriel.
"The memory was agonizingly brief. He had trudged no more than a few yards through the night when it was gone and they were cold again."(177)
In the first scenario, Jonas tells in the book how he is beginning to lose consciousness. He forces his eyes open. These present the concept that they have died or are dying.
However, Gabriel continued to stir against him. He warmed them briefly again with a little memory of warmth he had left. He makes it to the top of the hill and recognizes where he is at. He finds the sled and they ride it down the hill.
"For the first time they heard singing."(180)
This supports that they lived.