Yes, there would be no issue as there is no age limit in Gate exam and there is no minimum pass percentage in the qualifying degree while applying for GATE as well but if you want to join PSUs then all have their own age limits so overall you can apply for Gate exam after doing the job.

To check all about Gate and PSUs, you can go through the below articles and let me know if there is any doubt -

Gate 2018

Gate Eligibility 2018

PSUs through Gate

Good Luck!!!