Hello student I'm sorry to inform you but admission in IIT is not on the basis of rank obtained in Jee main. You need to appear in Jee advance and clear the cut off to get admission in any IIT's.

Cut off vary every year on various factors like level of question in examination seats available and total nunumber of applicants in the entrance examination.

For more details refer to the link mentioned - https://engineering.careers360.com/articles/jee-advanced-cutoff-for-iits/amp

Feel free to comment if you've any doubt

Good luck