A few suggestions from my sides may kindly be seen in this context-
1) Since your rank in JEE main
in 2019 is around 20 k and hence it is quite possible to have a seat in Computer - science in any of NIT college. Even if get a seat in other stream such as Mechanical, Electrical, Electronics etc in any reputed NIT, it would not be bad in terms of your future growth.
2) The employers of the IT companies would be interested to assess your presence of mind in the interview, the ways how you respond to the queries put forth by the members of interview apart from your confidence and sound clarities in the topics asked by them. You need not be necessarily a B.Tech in Computer- science, aspirants having other streams too can qualify in the IT companies.
3) I won't suggest you to drop this year with the expectation of better performance in the next year- it may happen otherwise. In the event of bad performance, you will be loosing a valuable year.
4) As you are stating that you may get BMS college Bengaluru with the branch of Computer- science this year, in that situation, you should avail it without having a second thought. In Bengaluru, you will get a number of IT companies approaching the campus of Engineering colleges for Campus - selection and with a little preparation prior to interview, there would be a fair chance of your selection in the IT company.
5) BMS college of Bengaluru has wide reputation in terms of teaching and arranging campus selection for the brighter students.
6) Don't think of dropping a year rather avail of the present oppurtunity.