Hello there,
The cutoff percentile depends on many factors. There is different cut-off rank for different branches of NIT. Also, there is Home State Quota and reserved seat for the SC, ST and OBC candidates, so it depends on your category as well. Also the cut-off rank changes every year depending on the difficulty of the paper,and the number of candidates appearing for it. So there are quite alot of factors determining the cut-off rank. If you are from the general category, and want to get admission in CSE in the top NITs, then you need to have 99 percentile atleast. The competition is very high. A minimum percentile of 97.5 is required atleast, to get admission in the lower NITs for the general category.
You can check the cutoff rank of all NITs in the link given below:
https://engineering.careers360.com/articles/nits-cutoff-for-top-btech-branches
Hope this answer helps you.
Good luck!!

The minimum percentile for getting an NIT is 89.7 percentile in General category , OBC is 75 percentile , SC is 54 and ST is 44