The CSAT paper (Paper-II) is qualifying in nature — you need at least 33 percent, i.e. 66 out of 200 marks.
Only GS Paper-I marks count for the prelims cut-off; a wrong answer in Paper-I costs one-third of the question’s marks.
Paper-II marks do not affect your ranking, but failing the 33 percent bar disqualifies you regardless of your Paper-I score.
The Paper-I cut-off varies every year based on vacancies and paper difficulty.