SVNIT is theoretical research-based while CEPT is more practice-oriented. If you are interested in pursuing a Ph.D. further or if you would like to get placed on-campus, then SVNIT is your place.
After matching your requirements focus on excelling at GATE to get structural engineering getting into structural engineering at SVNIT.
If you choose CEPT then you will have to work hard to get a job. It is well known in all of Asia and has one of the best civil engineers. The faculty is highly qualified, its alumni are working in MNCs and most of them get annual trips abroad.
Lastly, if you are not from Ahmedabad you will have to stay at the CEPT hostel which is an awesome place to stay, as you will see for yourself if you so choose to be.
Be mindful of the fees because both SVNIT and Nirma charge more about the quality they provide.