There's no way to know for sure what a Google Employee thinks of Bing unless you're that person working at Google.
I do have a friend though that used to work for Google and she actually preferred Bing Search and then after she lost her Job at Google she decided to apply for Bing and now works at Bing and has a much better job.
I love both Google and Bing search myself and alternate between the two as one does provide better searches than the other at times.