Encryption on the cloud with versioning
I'm assuming that you mean any time the file changes, it is re-encrypted with PGP. Here is a description of how PGP encryption works:


  


Whenever you change the file and re-encrypt with PGP, a new, independent session key is chosen. So what you end up with is a (potentially only slightly) modified file, being encrypted with a brand new session key.

All modern block ciphers, when used correctly, will protect against cryptanalysis, even when the analyst has access to multiple encryptions of the same (or slightly modified) plaintexts. Since PGP is generating a new, fresh, independent key, this would fall under the category of when used correctly. So, no, an attacker having access to all these encrypted versions gains no advantage in breaking the plaintext or the keys.