Marks keep changing from year to year, state to state and institute to institute. Anyways I can give you a brief idea. In general, You need to score around 60-70 marks and above to secure a nit seat in any branches available. And to get into top NITs, maybe in CS and IT branches, you might need to score 120-150 and above marks to be on the safest of sides to confirm your nit seats.

Best wishes. Thank you.