One of my friends studied at NITIE Mumbai, so I might be able to help you with your question. Here are some facts that I gathered from him about the process.
The number of applications received by the institute determines the cutoff for each course. It is, however, based on the GATE score rather than the rank. This is due to the fact that it is an interdisciplinary course, which means that any engineering student can apply for it. GATE score is used instead of GATE rank to ensure that they are on the same platform.
The trend of increasing cutoffs can be seen as the number of applicants increases year after year. As a result, I recommend that you aim for an 800+ GATE score to be on the safe side.nitie