Can I get seat in CBIT through mains marks??? I got 90 percentile

Hiiii Burla!!!! Yes you can get into CBIT through your JEE mains marks. 90 percentile is a very good percentile and very very congratulations for your score. To get admission in CBIT you will be needing a rank of around 25000.  So if your rank is around that then you can enter the college. You can check your rank from the below link.
https://engineering.careers360.com/jee-main-rank-predictor