According to the official website https://viteee.vit.ac.in/ , it says and we quote" For Indian nationals/ NRI/ PIO card holder, appearance in VITEEE-21 is mandatory to be eligible for B. Tech. admission under regular mode (Applicants under International/NRI quota exempted) . In case VITEEE gets cancelled due to natural calamities, qualifying criteria may be substituted with higher secondary marks or JEE-21 or a valid SAT. Applicants will be informed with specifics in such case" . So it is still that VITEEE entrance examination that is mandatory and only in cases of natural calamities the way it happened in 2020, will be JEE Mains score or SAT scores or your 12th marks that will be considered. So atleast until it is notified, it is only VITEEE score that will be considered in 2021. To be eligilble for VITEEE, you should have completed your 12th with a minimum aggregate of 60% in Physics, Chemistry and Mathematics/Biology. It is 60% for General Category/EWS/OBC and its 50% for SC,ST and Candidates belonging to Jammu and Kashmir, Ladakh , North Eastern states of Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim and Tripura.

VIT really has a very dicy admission system and is considered discrepant by many since it doesnt declare the Marks of a Candidate and directly declares the AIR. So besides VIT Score, it would be better if JEE Main Score is accepted and there are specific quota/reserved number of seats for JEE Entry and VIT Exam Entry. Considering VIT as one of the Top Private Institutes, I believe a rank anywhere around 15-20k, in JEE Mains will ensure you a seat in CSE at VIT Vellore, since under 12k, you can easily get Good NITs in Circuital Branches. All the Best.