GIC certificate only - no other financial documents are required under SDS.
Loan varies from bank to bank but you need a co-applicant in both with or without collateral, interest rates are 11-14% without collateral and 7-9% with.
I would like to add points to the above,
1. One year tution fees to be paid in advance under SDS
2. GIC to cover 1 year living expenses
3. Above two documents would have been good under normal conditions for SDS but to make our case strong it would be great to project some additional amount to cover 2nd year tution fees and living expenses and give an explanation in LOI
4. If you are mature Student, then a net worth certificate from CA would be great to show home ties.
Please note point 3 and 4 is not a Visa requirement but nice to have. With regards to Loan, SBI rate of interest is 8.5 to 9% (you may not get collateral free loan from SBI). ICICI, Axis and HDFC is 11% with collateral and 12% without collateral. If your credit rating is good and opted of decent university and have someone whose monthly take home is above 70K inr to become your garuenter then you can get a collateral free loan from a private bank. Here, is also something I would like to share: if you have an existing home loan, then you take an additional student loan from the same bank using this home loan property as a collateral. Including SBI all banks will give. At last, there are many student loan aggregators available and thier services are quite good and it's all free. Like Wemakescholars, gyandhan. I have taken help from Wemakescholars to get a student loan from SBI. There are many private players as well who can finance your student loan like prodigy Finance.