As per MHRD regulations the admission should be taken after GATE qualification and the admission should be based on GATE qualification (with 70% weightage to GATE score and 30% weightage to performance in the interview).
Even if you are GATE qualified in 2010, since your admission isn't based on a valid GATE score, you aren't eligible for MHRD stipend.It was clearly mentioned in the regulations that only those who are in the pre-final or final year of engineering program can give the examination and not those who pursuing a Masters program in engineering.
Even if u had given GATE examination with your B.Tech qualification and while pursuing masters, you can avail the assistantship only for a fresh admission and not for the program already pursuing.