short: Is there any way to view who has pushed a commit to a git repository?
long: git log shows me who created the commits, when and what are the commit comments. So I can know an original author of a commit. If such commit was pushed to a feature branch by the original author, I'd like to check who merged this commit to the production branch.
No, you would need an extra layer added to Git in order to record that kind of operation.
git log only display the committer and author, as recorded in the commit.
But that has no bearing on who is actually pushing said commit.
For instance, gitolite (an authorization layer) adds an audit trail mechanism, with logs.
See its log file format.