Hello Sumita ,

IIEST Shibpur is a really good college, the factor that affect the cut off rank is mainly the difficulty level and the no. Of people appearing for examination. 

Stating facts for the last Year's cut off for B.arch according to JEE mains paper 2 examination.

2018 : 

General 

Home state - Opening 901, closing 1376

Other state - opening 940 , closing 1372

SC/ OBC / ST ( might differ a bit but it's around these no. ) 

Home state - Opening 215 closing 237 

Other state - opening 41 closing 94 

This was for the first round. 

I think with this rank in JEE mains you can get half government colleges in your state , considering NATA score it's a bit low to get into top ranked colleges you need atleast 120+  

You can predict good colleges for yourself from the link below. 

https://engineering.careers360.com/jee-main-architecture-college-predictor

Hope this information was useful. All the best.