Hello Javed

JEE Main qualifying marks will be declared by National Testing Agency (NTA) after 30 April 2019. As the JEE Main exam is being conducted twice a year for the first time, it is difficult to predict the expected cutoff.
85 percentile score is considered to be a decent score to qualify for the Advanced exam as per the experts of various leading coaching institutes but this is also not clear. Nothing can be said exactly before the results of JEE Main April exam.

Good Luck!