The film deals about pride and ego. Zach and Avi try to teach Jake that one needs to accept his weaknesses and recognize faults and fears. Once stripped of pride then your ego will show itself, which literally happens in the elevator scene. He battles his insticts of selfpreservation which ends up in a clash between himself and his ego. Once seperated he can take back control of his own life. It plays further on the basic ideas repeated multiple times in the film:
"Our greatest enemy is your own inner perception, is your own ignorance, is your own ego."
And even better are Avi's words during the scene:
"The greatest con, that he ever pulled... was making you believe... that he is you."
So he's finally able to break his perception and finds liberation. There's so much more happening on this subject but this is I think more or less the importance of the elevator scene.