Hello Pankaj, first of all congratulations for your GATE score. Now, we can assess your chances of getting in IITs or NITs on the basis of previous year cut-offs. Firstly I would like to mention the closing GATE score of IITs for previous years available for General category (for CSE branch).
1) IIT Madras- 770 (in 2018)
2) IIT Bombay- 750 (in 2018)
3) IIT Kharagpur- 791 (in 2017)
4) IIT Guwahati- 770 (in 2017)
5) IIT Kanpur- 732 ( in 2016)
6) IIT Roorkee- 53.64 marks
7) IIT Hyderabad- 731 (in 2017)
8) IIT Gandhinagar- 600 (in 2017)
9) IISc Bangalore- 894 (in 2018)
10) IIT Dhanbad- 571 (in 2017)

Now, I would state the previous year's closing cut offs of CSE branch of NITs. (In 2018)
1) Central University of Rajasthan- 463
2) NIT Jalandhar- 544
3) IIEST Shibpur- 588
4) MNIT Jaipur- 628
5) NIT Bhopal- 625, 607 and 618 depending upon the M.Tech course you choose.
6) MNNIT, Allahabad- 707
7) NIT Goa- 552
8) NIT Surathkal- 711
9) NIT Manipur- 458
10) NIT Meghalaya- 453
11) NIT Nagaland- 449
12) NIT Puducherry- 513
13) NIT Sikkim- 481
14) NIT Agartala- 485
15) NIT Arunachal Pradesh- 453
16) NIT Calicut- 680
17) NIT Delhi- 615
18) NIT Durgapur- 525
19) NIT Hamirpur- 552
20) NIT Jamshedpur- 568
21) NIT Kurukshetra- 592
22) NIT Patna- 520
23) NIT Rourkela- 656
24) NIT Silchar- 505
25) NIT Trichy- 747
26) NIT Warangal- 759
27) IIITDM Jabalpur- 493
28) SVNIT Surat- 620
29) SLIET Longowal- 453
30) VNIT Nagpur- 632
Therefore on the basis of previous year's result you have chances to get NITs.

To get a more accurate prediction, use this college predictor link:
https://engineering.careers360.com/gate-college-predictor

Also to know more about the previous year cut off patterns, visit:

https://engineering.careers360.com/articles/gate-cutoff

All the best!
I hope this helps.