Jensen tells Olsen that he could make it to the Indian reserve, 90 to 100 miles away, in a day or a day and a half. In good walking conditions this might be just barely possible for a seasoned hiker; but not through mountainous terrain, in the dead of winter, with a foot of snow on the ground. Jensen has lived at the camp for three years, and would presumably know better.
Just before and immediately after autopsy is performed on the crew member who committed suicide by shooting himself, he is clearly visible breathing on the table.