Hi aspirant

Yes DTU is good for B.Tech.DTU will take admission on the basis of JEE mains and its cut off will be as simmilar to that of top NITs.

If you are preparing for GATE then you should be able to complete your course honestly because in GATE exam all branch papers from 1st year to final year  are asked .

You may join some coaching or you can prepare by yourself.

You can buy online preparation courses or pendrive courses.This would be helpful to prepare for GATE.

Hope this was helpful.