Actually, according to the interview with him, he said that the drag from the tangled parachute probably only slowed him down from 120mph free fall speed (his estimated terminal velocity) to the 80mph impact speed. (Yeah, that extra 40mph maybe would have made it fatal, but 80mph would usually be fatal too).

He survived by hitting a very thick section of underbrush that absorbed the majority of the impact of his fall. He apparently left a very big and defined imprint where he landed, which shows just how much damage the underbrush took.

Where he fell was kind of lucky on his part. He was spinning so fast he couldn't aim or control his direction at all. Less than 100 ft from where he fell was a solid concrete airfield (where he would have been dead on impact) and in the other direction was water (where he would have been knocked unconscious and drowned).

Of course this "luck" only followed the severe unluck immediately preceding it. The reason for the parachute failure, he says, was "the cords seemed to be catching on part of the parachute container on my back, which is a one-in-a-million chance."