Should I drop a year for the JEE or take IET Lucknow's CSE?

My brother is a student of CSE at IET Lucknow, so I think I can give you some information regarding the CSE branch at the institute. 

CSE is such a branch in which students excel even if they do not come from a well-known college. Doing well in CSE does not wholly depend upon the college name or the infrastructure. 

Alumni - achievements: 

The students of the CSE branch at IET Lucknow perform well in all fields, be it GATE, CAT, or placements.

• A few years back, Shivang Bansal was placed at Microsoft with a package of 37 LPA last year. 
• In 2018, Apoorva Bansal was the topper of the CAT examination in the girls’ category from the Lucknow zone. 
• Raghvendra, one of my brother’s seniors, got AIR 16 in GATE from the CSE branch. 

Placements:

Here is the recent placement highlights for IET.

So, opting for CSE at the IET branch will be a better option than taking a year drop for JEE. You can keep preparing for JEE side-by-side with college.