Their is no special cut off for any course at sastra, it depends on the availability of seats. It varies every year. However, on an average, it can predicted that for CSE branch at SASTRA university, your rank should be within 500 in stream 1. The cut off changes every year, but a rank of 500 will keep it safe for you. All your board exam percentage contribute greatly to your selection here, especially in stream 2.

I hope this helps you!