Hello student number of aspirants vary every year but as per previous year records around 50,000 - 60,000 aspirants appear in Indian judicial services out of which around 7500 candidates clear the entrance examination.
Eligibility - candidates must hold a LLB degree from a recognized institution.

For more updates refer to the link mentioned below - https://doj.gov.in/appointment-of-judges/vacancy- (https://doj.gov.in/appointment-of-judges/vacancy-positions)

Feel free to comment if you have any doubt

Good luck