what effect fate or human will does to Jocasta in　Oedipus Rex?

I'm not sure I understand your whole question. Certainly Jocasta Knew her fate even when Oedipus was born. Both Laius and Oedipus take steps to avoid their fate but we know it is a done deal, so to speak. Jocasta actually becomes a willing participant after fate has begun to take its course. The fact she is going to marry some young dude that killed her husband should have tipped her off!