If you want to opt for M.Tech in GIS, MNNIT Allahabad can be a very good option. The placement is also quite good with many alumni working in companies like L&T, ISRO etc. According to the students, the minimum package is somewhere around 5 LPA, which is a good amount given this field. However I would recommend that if you get a chance, you should go to IIRS Dehradun for the same course as it has facilities better than MNNIT and the placements are also great.

Hope I have answered your question. All the best!