This article will help you understand how Groups communicate between Commerce7 and Mailchimp with the WGits for Mailchimp integration. For more information on how to create segments please see Mailchimp documentation.
Groups sync over to Mailchimp as Groups, not as segments. Segments can be dynamic in Mailchimp, whereas groups are not. We do not sync to segments however, a Commerce7 Group can be placed inside a Mailchimp segment as used as a filter.
Use your Commerce7 Groups that are synced over from Commerce7 to create filters for your unique Mailchimp segments.
You can set up Mailchimp segments that will dynamically put customers into different segments based on LTV (Life Time Value). The LTV value is passed to Mailchimp so you will be able to use this to build various segments or tiers.