Prismic doesn't support native integration with Google Analytics or third party services like Google Tag manager, Mailchimp, Facebook Lead Ads, AddThis, Quickbooks, or Disqus. This is something that you would integrate with your website application directly in your frontend.
Are you a developer? If not, then get in touch with your development team so they can help you do this.
Check out our full walk through on how to add comments with Disqus.
Luckily, if you have an Google Analytics account, this process is as easy a copying and pasting some script and adding some authentication details. If you want to learn more about how to add Google Analytics to your web application, you can visit their website.
A/B Testing with Prismic's Experiments feature
For A/B testing in Prismic you can set up experiments, with these you will also still need to add your Google Analytics configuration on your applications frontend.
You can learn more about our Experiments feature here:
Hopefully this makes things a little clearer so that you can begin to take advantage of these third party services.