What happens to contacts in an automation if i pause it?

If an automation is “paused” the contacts will still remain in the campaign and automation but the automation will not run. None of the events will be triggered or executed. 

Published/Unpublished

Click the toggle switch to publish or unpublish the Campaign. Ensure that you do not publish a Campaign until you’re actually ready for it to go live. You can also schedule to publish or unpublish a Campaign at a future date by selecting a time and date.