Based on the fact that in the movie when Jake fell from the Dragon Gunship in the final battle, he landed on the leaves/vines/branches in order to slow himself down. So, in theory if somebody did the same, they could probably survive the fall. Also take into consideration if a human did it, they may not due to the difference in body structures.
EDIT: The Na'vi are also considerably different in bone structure from humans, and dark blue skin wouldn't show bruises very readily. It's likely if not certain that a human attempting such a stunt as a skydive from the Hallelujah Mountains without a parachute would break every bone in his body.
it is believed that Tsu'tey survived his fall off the Valkyrie only to be killed by Lyle Wainfleet. (one of the cut deleted scenes)