You should score more then 125 marks in JEE Main to get admission in NITs in general category other state quota. Cut off varies according to the branches as well.

You should try to get more then 230 marks to get CSE branch in top NITs in general  category other state quota.

Good Luck!!

To get admission in lower or average NITs, you will have to get 150 or above but if you wish to get top NITs and in top branches then better to get 230-250 as this would be the safest score to get admission there. So plan and prepare accordingly and for reference you can go through the below provided previous year cut off as well -

Jee main cut off 2017

Hope this helps!!!