my rank is 31489 in jee mains , can i get cse, IT in any of iiit?

First of all, You need to write JEE Advanced to get admission into IIT.

Since you haven't mentioned your category. I am assuming it to be general.

With this 31489 CRL RANK, a s per the previous year cutoff as a General  category you should have a decent chance to get a seat even in NITs, IIITs & GFTIs.

If it is category rank, the chance seems less to get a seat in NITs, IIITs & GFTIs.

To know your other best admission possibilities of Institutes & branches in JOSAA & State counseling as per your percentile, You can use JEE Main College Predictor tool given below.

https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Thank You