Hello roopesh

Well 80 percentile is not that good considering general category. Approximately it will not lead you to any nit but still keep your fingers crossed as cut off is still not released. Till then you can predict your rank by rank formula. Suppose 874469 are the number of candidates appeared for the January exam. So rank formula is (100- your total score) * 874469 / 100. By this formula the rank which will come will be aprrox. You can also check last year cutoff's for more information and category wise rank.

Hello Roopesh. Welcome to Careers360. I would like to tell you that the second exam is yet to take place in the month of April. So you can appear again in it if you are willing to take admision in NIT. Usually the cutoffs go very high of NITs. I am sharing a link with you. You can refer it to check previous year NIT cutoffs. 

https://www.google.co.in/amp/s/engineering.careers360.com/articles/jee-main-cutoff-for-top-nits/amp

Hope this answer helps you. Good luck.