HubSpot can set Salesforce Lead Owners through an Import. This is achieved by Importing a linked Salesforce Owner email address into the HubSpot Owner property. To see the process for importing HubSpot Owners please reference this article: How to Import HubSpot Owner
Linking Salesforce Owners to HubSpot will happen automatically, as long as, the Email Address and Name match HubSpot Owners. A HubSpot Owner will be created for each HubSpot User added to your portal. If the Owners are not linked, then the Owner changes will revert upon a sync with Salesforce to the original value.