Graduate Aptitude Test in Engineering (GATE) is an all-India examination which is conducted jointly by the Indian Institute of Science and seven Indian Institutes of Technology

It’s not necessary to take one year Gap for preparation of GATE. It all depends upon the capacity of the student. One can clear the GATE Exam while pursuing graduation too

But, you can take a one year gap for preparation of GATE exam, it would be a good decision as you can get a good score if pays your full attention for the preparation of this exam.

But there are a few companies which have some norms regarding 2 year gap, they do not recruit people with a two or more year gap. So I will suggest you try not to make a two year gap in between the studies