Pages doesn't let you share or export directly to Google Docs, so you're left with kind of clumsy methods if you have to start in Pages and get to Google Docs. For instance, you can email a Pages file to yourself, open it on the desktop and save it / upload it to Google Docs. Or email it to yourself, download it in the Mail app on the iPad and then choose to 'Open In' the Dropbox app, then use a 3rd party app like Office2 HD to access files from Dropbox and directly from your Google Docs account.
If you don't need Pages, you may want to work just with Office2 HD.
You can send a Pages document directly to your Dropbox. Do the setup here, which will provide you with your own unique "send to dropbox" email address.
Your file will appear in an "attachments" folder, in your dropbox:
http://sendtodropbox.com/
Trust me, this works like a charm!
Edit: you can use this method in any App that supports the emailing of attachments, such as Photos.
On the iPad, when a file is selected within the Dropbox App, an "open in..." menu pops up. You would the select Pages. Not a perfect solution, but workable. Unfortunately though, Pages will open a "copy", not the original file.I'm not sure this really works for the solution required. How do you open files to edit from DropBox using pages in this ?