Hello Katheek, 

               See situations like this  all depends on your will power, interest, caliper and patience.

                See studying in IIT means studying in one of the top engineering colleges in India. But that doesn't mean that you will surely have a bright future as there also you need to work hard.Thus studying in NIT also almost means the same but yes IIT is always best.

               So now  if you feel that you can do it (ckear jee advance) next year u have a strong interest towards it, have caliprr to work hard n clear the exam  you must surely go for the best. But if somewhere if yoi have even 1% of doubt that somehow you may noy clear Jee Advance next year then u should go for NIT as this 1% may let your 1 precious year of life go in vain.

 Good Luck