It has been clearly reported, but in case folks are not aware: PRISM is not a system for deep persistent access into tech platforms, it is the internal NSA designation (code name) for data sourced via FISA court orders. The FBI actually secures the court order and then requests the data.

https://en.m.wikipedia.org/wiki/PRISM

If a company stores data about you, it is possible it could be subject to a FISA request. Data which is end-to-end encrypted would still be provided if it satisfies the criteria in the FISA court order. But it would be up to the NSA to try to break the encryption. Metadata might or might not be encrypted.