It is difficult to predict your exact qualifying marks or JEE Advance Eligibility as first time JEE is being conducted twice and rank will be based on NTA percentile score. But a score of more than 85 percentile should be a good score to qualify JEE Advance.

You can use this formula to calculate your expected rank-

874469 are the number of candidates appeared for the January exam. So rank formula is (100- your total score) * 874469 / 100.

If the number of candidates for April exam increased to 1400000 then your final rank shall be (100- your total score) * 1400000/100

Good Luck!