The Pavis cult is really quite small, likely less than 2000 initiates in the world. Maybe 300 reside in New Pavis, 500 or so reside in the Big Rubble. As many as 200 reside in Pavis County. Another 1000 belong to the Zebra Tribe – the so-called Pavis Survivors. I suspect the cult has another 1500 or more lay members in New Pavis and another 300-500 in the Big Rubble.
That would make Pavis the fifth largest group of initiates in Argrath’s New Pavis (after Orlanth, Ernalda, Humakt and Storm Bull), but easily the most important cult inside the Big Rubble, which sounds right to me. It also has far more lay members than initiates in New Pavis – probably some 5 lay members for every 1 initiate. The cult of Pavis is very much part of the religious landscape in New Pavis, even if his mysteries are not widely participated in.
The importance of the Zebra Tribe in the magical ecology of Pavis should not be understated. Although the main temple is that of New Pavis and the most sacred places are in the Big Rubble, it was the Zebra Tribe that has kept the idea of Pavis alive.
from Pavis: Gateway to Adventure (2012)
Also, this would mean that probably 2/3rds of the humans that reside in the Big Rubble are Pavis initiates. After that it is Black Fang and Daka Fal. Orlanth, Yelmalio, Yelorna, and Lanbril are all tied in a distant fourth place.
There are some 5000 members of the Zebra Tribe. About 30% of the adults are initiates of Pavis.
Meanwhile a cult like Black Fang might have a total of 300 initiates, but no lay members. There are no casual members!
In contrast, Lanbril might only have 150 or so initiates in the area, but many times that number of lay members. Heck, I could imagine there being 750+ lay members of Lanbril in New Pavis, pretty much the whole criminal element in the city!