Employment pass

If the earlier salary was 5.6 ( was on Epass)and the new salary is lesser than what are the chances of  Epass? Does the pass downgrade too?

The chances of EP approval depend on the salary in comparison with the market mean, not on what you earned in a (potentially overpaid) previous job.
You can check the online SAT tool to find out whether you qualify for an EP at the new salary.