what percentile in jee main should a general category student need to get admission in Nit-durgapur and IIEST ?

It is depends on every years and department

In NIT durgapur the previous years cutoff is 1 to 49500 rank ----------- the percentage is above 93 %in jee mains

For IIEST college it is also depends on department cutoff. This is one of the best college in india .
As per previous years cutoff the rank should be between in 1 to 50000 rank in jee mains so the percentage is above 91 %

For more information about NIT durgapur you can visit here
https://www.careers360.com/university/national-institute-of-technology-durgapur

For more information about IIEST you can visit here

https://www.careers360.com/university/indian-institute-of-engineering-science-and-technology-shibpur

Thank you. I hope this answer helps you.