In my view, the decision can be based on the following factors.
1) Whether job is the need of the hour for him;
2)What are the financial compulsions - whether he can afford to leave the job and pursue M.Tech now.
3) If he skips M.Tech now, how much difficult or how much easy it will be to secure a seat in M.Tech in NIT again.Whether this job experience will help him get a seat in M.Tech in NIT latter. I known one has to shed lot of sweat and survive stiff competition to secure a seat in premier institutes like I.I.T or NIT.
4)NIT or IIT are such brand names tat one can secure a job easily after his M.Tech education.
5) M.Tech open sup another avenue of teaching in Engineering Colleges.
In my view, if financial crunch is not the reason to skip, my vote is for M.Tech in NIT.
All the best.
B.Saikumar