Yes, MCA is equivallent to BTECH, BCA+MCA= BTECH. After BCA directly MTECH can not be preffered. And for it is good to MCA after BCA and then for heigher is MTECH, because BCA includes only the basic knowledge of Computer Science.So yes, An MCA student is eligible for the GATE exam.

In my opinion, If you are planning to join an M.Tech then it's not a good idea as you have post graduation MCA already.

If you want to join PhD in IITs or IISc, you have two options, which will be considered for the selection of the candidates for PhD are,

UGC NET JRF in Computer Science.

GATE Computer Science.

Age limit for NET JRF is 28 years for general category and 5 years relaxation for OBC, SC, ST and women. And there is no age limit for NET Lectureship.

By qualifying NET you can apply for the post of Assistant Professor in Universities.

Hope it helps!

Well i see that you want to do mtech after mca. Well technically it seems to me ok, because as you know the btech degree is equivalent to bca + mca. Means first you do bca then you do mca. So basically after doing both you have a degree equivalent to btech . So you can give gate exam and do mtech.