i am getting approximately 50 in ece branch .Is there any chances for psu and iit for mtech?

Chances are decent for admission in IITs and for PSUs recruitment as well so below I am providing you the Gate college predictor which will help you to get an idea where all you have admission and recruitment chances as per your above said score -

http://www.engineering.careers360.com/gate-college-predictor

And below I am also giving PSU list where you can apply according to the eligibility criteria -

http://www.engineering.careers360.com/articles/psu-recruitment-through-gate-2017

Wish you luck!!!