The minimum percentile to get admissions in IITs'S/NIT's will be decided by the counselling committee. That is you have to undergo counselling under JOSAA( Joint seat allocation authority ) the college that will be allotted you in the counselling is your final college and that is as per JOSAA.
JK AICTE PMSSS scheme will only give you financial aid for your studies. The cutoff for you will be the same as for ALL India Candidates. Hence, there is no minimum cutoff for taking admission under pmsss in NIT'S/IIT'S.
Read a related answer below on how to get admission in IIT'S/NIT'S .
How to get Scholarship for studying in IIT,NIT and IIIT - pmsss.in
I want to pursue my studies in IIT/NIT/Institute of national importance , am I eligible for PMSSS scholarship? - pmsss.in