Unfortunately, the only thing you can do if you get stuck in a falling elevator is tuck your head between your knees and kiss your butt good-bye. It’s a simple matter of physics. Let’s say, for example, that your falling elevator reaches a terminal velocity of 100 feet per second. Even if you are capable of a leap of Michael Jordan proportions, you’ll only reach a speed of maybe 5-10 feet per second. (For context, a sprinter doing a 40-yard dash in five seconds is moving at 24 feet per second; but that’s horizontally, of course.) That leaves you with a net downward velocity of 90-95 feet per second. Ouch.
(Source: The Straight Dope)