Sardar Vallabhbhai National Institute of Technology, Surat

Your expected JEE Main AIR is about 48373. The last year closing ranks in asked NITs in your category for neutral gender in civil engineering under OS and HS quotas are given below.
1. SVNIT : (HS 84751 and OS 34478)
2. VNNIT : (HS 39678 and OS 32268)
So from above for other state quota (OS) your JEE Main percentile should be above 97 while for home state quota (HS) your JEE Main percentile is enough if belongs to Gujarat.

No, GATE Score is a mandatory requirement for M.Tech courses at SVNIT. So, you can not get admission here without GATE score.

Please check for your eligibility to pursue a B.Tech. in Electrical Engineering from Sardar Vallabhbhai National Institute of Technology from the link provided below. Admission process for this particular course is also mentioned at this link:
https://www.shiksha.com/b-tech/course/b-tech-in-electrical-engineering-sardar-vallabhbhai-national-institute-of-technology-surat-61965

You can visit this link.
https://www.shiksha.com/college-predictor

Nom the board marks are just for eligibility. You need to score an percentile above 95 to get admission in not Surat. On the basis of board marks you can just clear it's eligibility criteria.

No, you cannot be eligible for NIT Surat in chemical engineering. As you have an low score in Mains. You should now focus on April Mains exams and score good marks to get NIT Surat.