A hub site in SharePoint links together sites based on certain shared features. You can use this feature to make it easier for your users to find related content.
The ShareGate migration tool can migrate the hub site from a source environment to your destination, but it will not be able to keep the association to other sites.
Note: the ShareGate migration tool does not support the migration of Hub navigation (cascading menu and mega menu).
You will need to manually recreate the associations in the destination environment post migration.