I will never advise that you do this because the result can be fatal and you definitely won't be around to tell the story. The thing is you are not very sure of the number of floors the elevator would cover before hitting the ground.
If the elevator only covers few floors, you may decide to jump, but that doesn't mean you won't get hurt. But if the elevator covers so many floors, jumping in a falling elevator can be fatal. In whichever case, people are always advised not to make such an attempt if they are stuck inside a falling elevator.
If you find yourself in a situation like this, you can try other things like lying down on your back. I won't suggest that you sit because the result will be very bad for your back. However, sitting is better than standing because the muscle and fat in your buttocks will help you absorb and reduce the forces of the impact.