How does it matter what the final cutoff would be? Your marks along with your fate has already been sealed. It cannot be changed.
Why do you need someone eles's validation to know how many marks you'll get in GDPI? The person you're asking this question was not there in the room serving tea that he overheard the interview. In interview, it doesn't matter what you're answering, what matters is how you're answering it. So, no matter what you tell to people what you answered, they cannot judge your marks.
The interview marks depend on a lot of factors, and what you tell to people is only one of those -what you answered to a particular question. Factors like, your hand gesture, your eye contact with the one asking the question, your posture, you voice modulation, your confidence, these cannot be judged by anyone, but the interviewer.
Also, stop this negativity of the final cutoff. What if I say that I think the cutoff will be 57-58? You'd agree to it? No, right!! Because, you, in your mind have already set a cutoff, according to the marks you believe you're going to get. Some may say the cutoff will be 55, some 54 or some like me even 58. Don't indulge in these things as it is worthless. The reason is, you will keep on making the cutoffs according to your marks, but on 30th, say your roll number is not in theat PDF, you'll be devastated. All this I'm saying is with experience.
Stay balanced. Do not be too optimistic nor be too pessimistic. Either of these inclinations will hurt you. And, not just momentarily, but rather in a very long run.
On 30th, two things will be sure. Either you're going to SBI, or you'll make it to some other place. This is what is important, right! Moving forward. Not staying back because of one result. If you just keep thinking of failure, you'll stop moving forward and you'll be stuck.
Being confident is a very good thing, but there should always be these two words somewhere in your brain, always - "what it?"
Read books, watch movies, eat a lot, just don't speculate.