hii

the marks would be told by the end of the month by NTA while you have to know the ranks to know wheater you can get NIT or not so please fallow the below method

To calculate you rank you can use the formulae given below - 

Rank=(total number of students -(percentile*0.01*number of students))

Where total number of students who appeared for the examination is 9.65 lakhs

please check the links for more info

Link for cut off

Https://engineering.careers360.com/articles/jee-main-cutoff

For jee advance

Https://engineering.careers360.com/articles/jee-advanced-eligibility-criteria

regards