I have 869 rank. Can i got C S branch in vellore

First of all congractulations for scoring such good rank and yes , with this rank you'll be able to get the seat in the institution , though the ranks are subjected to change as they depends upon various factors like number of applicants fill the form, number of applicants finally appeared in the exam, number of questions asked in the exam, difficulty level of the exam, performance of the candidate, previous year's cut offs trends availability of seats in the institution but if we look at previous years cut offs of CSE the last closing rank in 2016 was aroung 7k so there's no chance of you facing any problem in admission in vellore campus.

Good Luck!!