I did a quick search on this and I could find a document that suggests this:

At any given point of time, the maximum number of Ph.D. students allowed should not exceed 8 students for a recognized Professor, 6 students for a recognized Associated Professor and 4 students for a recognized Assistant Professor.

Read point number 4 on page 2 of the guidelines for the Recognition of Fellow Programme of Self-Financing Autonomous Management Institutions recognized by AICTE towards Equivalence to Ph.D Programme of Indian Universities.