As far as jee advance is concerned the rank is too much to get admitted to any IIT. But you can check out the cutoff for the different institute which offers course on the basis of JEE advance scores like the RGIPT, IIPE,IISC, etc.

And a candidate cannot get admitted to NITs from the likes of JEE advance rank, you need to mention the jee main score to know the NITs which your nephew can be admitted to.

Good luck!