GATE

Yes you can, there are online coaching available so look for classes from Byju's, Mbaguru etc.

minimum is interest

It may be tough to crack GATE for M.Sc CS students but not an impossible task. If you plan and prepare well you can easily crack GATE after M.Sc CS degree.

Satyanshi dropping an year won't be a good idea because if you don't get a good score next year then you would repent wasting an year.
Better would be try for admission in some good private university and side by side prepare for GATE. These days we have so many good private universities imparting quality education to the students around the world. They offer you admission on JEE scores/ tests conducted by them/ your marks in 12th. Some of these also offer good scholarships based on any one of the above mentioned admission criteria.

to crack GATE exam, your engineering concepts must perfectly clear to you.so, from first year, I will suggest you to build up your concepts from the standard books available and practice as much questions as you can.all the very best!!!!

Go for what you really want to achieve.