The Auctiva "Template" can only be used in the creation of a listing with the Auctiva one-page listing editor. The template provides both background and structure to the eBay defined Description section of a listing, like the fancy backgrounds and image placements. It also has special tags for use with features and text you can pre-can using Profiles for that purpose. So, the template feature can't actually be transfered to eBay, as it's more like a script to follow in using Auctiva's listing builder.
However, you can take an Auctiva saved listing created using a template and export the HTML using the icon for that purpose on the Auctiva Saved Listings page (the icon is to right on each saved listing). It's essentially a copy and paste process to take the code to eBay's one-page lister and paste to the Description section using HTML mode.
You can also simply submit/schedule listings directly from Auctiva, and avoid the copy and paste hassle.
I hope that helps clarify and provides a high-level on how to accomplish the task.
Danno