When you connect Google Analytics, it will pull straight from Google for this data. In these cases, it will report the "Users" field from the time that Google Analytics was connected, and subsequently each time that an individual logs back into the platform (assuming GA is connected).
For instance, this is a test account showing the field via TapInfluence followed by what Google Analytics reports:
In each case, TapInfluence will report Monthly Unique Visitors, which will be considerably different than Pageviews, as page views will capture each time an individual loads a page (to include multiple times). While Users/MUVs will capture unique visitors, which is what Brands are interested in, since this would be the count of people that they are reaching.
If the reported number varies considerably, please contact support and verify that your account is linked to the appropriate Google Analytics account.
Have additional questions or issues? Email firstname.lastname@example.org