Hello Kurimilaakil Sagar, the EWS category affect much in getting seat in counselling both through state as well as in All India Quota.Both in Medical and JEE it affects much during the counselling.
For Example
Last year state closing rank for University College of Medical Science

General State candidate - 2748
EWS state candidate - 5698

Last year cutoff for National Institute of Technology (NIT) for Information Technology

General All india Candidate - 5403
EWS All India Candidate - 7261

As you can see that a person with of 7261 gets the same branch as the person with 5403 gets, so EWS certificate helps much in getting a better seat with the lower rank as compared to General candidate.