Software Revenue Build

I'm working on a revenue build for $NOW and at my wits end on how to model revenue other than just applying a YoY growth rate. 

For those on the buyside or sellside who have done work on $NOW or other software/SaaS companies, how have you built your revenue models? How do you break it down to P x Q if the company doesn't give customer count, contract duration, NRR or any other customer metric? Is there any way to use RPO or deferred revenue and convert that into a revenue forecast?

Thanks in advance for the help/insight