Most of my Googler friends had never heard of it (I've mentioned I've been playing around with it for a project lately). I imagine that it's like any large tech company with a well-educated workforce: you'll have some folks who like to keep up-to-date with the latest tech and try it out in side projects. Even Haskell had a few passionate supporters while I was at Google.

When I left 2 years ago, there was no "pressure" to use Go for new projects but a number of projects were adopting it anyway, since it had been blessed with "official language" status and a lot of Google infrastructure worked with it.