Hey Aditya,

You should better focus on preparing for JEE Advanced examination inspite of worrying about the rank. If your preparation is good and the performance is also good then you can get CSE branch at any IIT.

You can check the previous year rank vs cutoff for JEE Advanced here:

https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwjtqfu8h-7hAhVGWysKHfhKBfQQFjAAegQIAhAB&url=https%3A%2F%2Fengineering.careers360.com%2Farticles%2Fjee-advanced-cutoff&usg=AOvVaw3hoCGu2F9rFAjfMofymJnU

Good luck !