Updated: May 2017
You can sync your Gmail account with Outlook for Mac 2016 but you first need to add the account to Outlook. See Set up Outlook on your Mac for instructions.
At this time, Outlook for Mac 2016 support of Google Calendar and Contacts is only available to Insider Fast participants who have an Office 365 subscription. It will be available to all users worldwide later this year. See Sync your Google account to the Microsoft Cloud for more information.