I got 80 marks in JEE but I didn't write advanced exam. Can I get a seat in an NIT?

Dear, Admission in IIT and NIT are two different things. Advanced is mainly for admission in IITs and JEE Mains is for admission in NITs and IIITs, so it's not mandatory to give Advanced paper for admission in NITs. You can go through counselling information on JoSAA website. All the best.

Hello, Kindly visit on Shiksha college predictor: https://www.google.co.in/url?sa=t&source=web&rct=j&url=https://www.shiksha.com/b-tech/resources/jee-mains-college-predictor&ved=2ahUKEwjPs-iFqpTcAhWMRY8KHariB-kQFjAAegQIBBAB&usg=AOvVaw1N9BzFtyUCP4JU-2UQHQ0H.