Dear Student,

According to the eligibility criteria, graduate degree from recognised university along with cut off marks in the respective subjects in the entrance exam is needed to take admission in IISC and IISER.
Until and unless you crack the exam and get a good rank, your gap year won’t matter.

Admission at IISER -Admission to the MS programme will depend on results from IISER TVM's national level online screening exams in each topic. Interviews performed by the individual schools will be used to choose among the candidates who were shortlisted as a result of the screening test.

Admission at IISC - 50% written test and 50% interview make up the selection process. Based on their GATE scores in BT, BM, EC, EY, MA, PH, and XL as well as their JAM 2022 scores in BT, CY, MA, and PH, candidates will be short listed for the test and interview.

To know more about these two exams -

https://www.google.com/amp/s/dqxeclau.top/university/indian-institute-of-science-bangalore/amp
https://www.google.com/amp/s/engineering.careers360.com/exams/iiser-aptitude-test/amp Hope this helps,

Good luck.