If you're integrating with Salesforce or Zoho CRM, this article may not apply because you're most likely using GA Connector API-based integration.

To push GA Connector info to GTM data layer, use the following JavaScript code:

 

To make sure that GA Connector is fired by the time this script is run, use the tag sequencing functionality provided by Google Tag Manager:

Tag sequencing

It allows to set the script from the article to fire after GA Connector.