Hi aspirant

You can do M.tech from IIT Gandhinagar only when you are qualified GATE and have enough cut off score.

If you have completed ECE then you should prepare for GATE entrance exam and appear in the exam.

Know more about GATE exam here: https://engineering.careers360.com/articles/gate-eligibility-criteria

You can check the cut off of IIT Gandhinagar here: https://engineering.careers360.com/articles/gate-cutoff-for-iit-gandhinagar

Hope this was helpful.