Hello dear, 

The number of students selected for jee advanced rcompletely vary year by year, like in year 2016 ,approx 20000 students were selected in jee advanced  and in year 2018 30000 students approx are selected .If the IITS fixed the percentage criteria for qualifications .Then it is hard to predict the number of students .

Hope this helps you. 

Good luck. 

HELLO!AJEET

Students who qulaify in jee mains can appear in jee advance examination.In 2018 total 224,000 students were allowed to appear for jee advance examination,this number had gone up from 220,000 in 2017 and 200,000.This year also 224,000 students will be allowed to appear for jee advance 2019.JEE MAINS qualified applicants are allowed to appear in JEE Advance examination.

You can ask if you have any other queries.

GOOD LUCK!