JEE Advance Maximum Marks are not defined. It varies every year So it is difficult to predict marks as exam pattern and marks change every year but you should try to score more than 45% marks to get CSE branch in top IITs. You can also check the previous year cutoff of JEE Advance with the given below link.

https://engineering.careers360.com/articles/jee-advanced-cutoff

Good Luck!