When printing Customer Statement there are two types of the Advanced PDF/HTML Templates: Standard Statement PDF/HTML Template or Standard Multi-currency Statement Template. It depends on Multi-Currency Customers Feature. To find this feature go to Setup > Company > Enable Feature > Company tab under international.
When printing Customer Statement you would like to have ability to print Customers fields on Customer Statement like Subsidiary or Name. The syntax for printing on Customer Statement is following ${customer.<id>}. Please see some fields examples below:
Subsidiary: ${customer.subsidiary}
Customer Name: ${customer.entityid}
For printing Custom Entity Fields which are applied to Customer record is the syntax similar ${customer.<custentityid>}.