Hello Jithu,

You can still appear for the GATE 2019 even if you have back paper in the last semester. See, whatever you wish to pursue in future, you should always go with that. I would suggest you to apply for PSU as well, if you go through, its well and good.

But, in today's competitive world having a graduation degree is merely a thing. Every other person has completed their B.Tech. Thus, i would suggest you to go for M.Tech first in your area of interest and later apply for the PSUs.

All the best!