As an admin user you should have the option to embed a Google Calendar into your instance through the use of an HTML widget, however the option to sync them into a Jive project calendar is not currently in the product. That being said, looking around the Ideas for Jive space I did find an example of where this, or a similar idea, has been suggested (Embed any Google apps: docs - Presentations - Spreadsheets - Forms - calendar), so would encourage you to help vote up that idea to help raise awareness with our Product Management team.
Thanks for this Jesse. I added a comment to the @Embed any Google apps. . . Idea that would add additional features.