I found a previous discussion about this. Its similar but doesn't' answer the question entirely.
http://forum.gravityhelp.com/topic/capturing-user-name-to-use-as-posted-by-author
Were looking to setup a form to allow users to submit content. We setup a test form and the content, image, and title are pushed to wordpress posts beautifully. Except for the authors name. Any ideas on how we can make this happen?
Our site is http://www.communitynewspapers.com and you can see the submit a story form at http://www.communitynewspapers.com/contact_us/submit-a-story/
You'll see that we have the authors name as a field but like I said before its not pushed to the wordpress post.