By importing a snapshot of your Google calendar into Outlook, you can see it alongside other calendars in the Outlook Calendar View. To keep the imported calendar up-to-date, subscribe to the Google Calendar in Outlook. If you don’t, the only way to update it will be to import another, more current snapshot.

Subscribe to your Google Calendar

An Internet Calendar (iCal) Subscription keeps your Outlook copy of your Google Calendar up-to-date.

1. Log in to your Google Calendar account. 

2. In the left column, click My calendars to expand it, then hover over the calendar that you want to add to Outlook as an Internet Calendar Subscription. Select the three dots to the right of the calendar name, then select Settings and sharing.

3. Near the bottom of the page, under Integrate Calendar, locate the Secret address in iCal format box, then select the   Copy to clipboard button.

4. In Outlook, select File > Account Settings > Account Settings.

5. On the Internet Calendars tab, click New. 

6. Paste the address you copied in step 3, by pressing Ctrl+V, then click Add. 

7. In the Folder Name box, type the name of the calendar as you want it to appear in Outlook, and then click OK.

When you start Outlook, it checks Google Calendar for updates and downloads any changes. While is Outlook open, it also periodically checks for and downloads updates.

Import a calendar from Google Calendar

1. Log in to your Google Calendar account. 

2. In the left column, click My calendars to expand it, then hover over the calendar that you want to import from Google Calendar. 

3. Select the three dots to the right of the calendar name, then select Settings and sharing: 

4. Under Calendar settings, select Export calendar.

The Internet Calendar (.ics) file is immediately saved as a compressed (.zip) file to your Downloads folder. 

5. In File Explorer, right-click the compressed file, then select Extract All. (This option removes compression and save the .ics file; then you can import it into Outlook.) 

6. In Outlook, select File > Open & Export > Import/Export.  

7. In the Import and Export wizard, select Import an iCalendar (.ics) or vCalendar file (.vcs), then select Next. 

8. In the Browse window, navigate to the .ics you saved in step 5, select it, then select OK. 

9. Select Open as New. The items are automatically imported into your calendar. 

The calendar opens in side-by-side view in the Outlook Calendar. It’s also added to the Navigation Pane in Calendar view, under Other Calendars.

Tip: If you don't plan to use Google Calendar anymore but want to keep your events, you can import your Google Calendar to Outlook so all of your appointments are integrated into one Outlook calendar view.

For the most up to date instructions on how to do this, please check out the following help article from Microsoft:
https://support.office.com/en-us/article/See-your-Google-Calendar-in-Outlook-C1DAB514-0AD4-4811-824A-7D02C5E77126