I figured out what I have to do, sorta...

I have to preregister the variable for use in another template. So I tried creating a plugin/hook to threadbit_display with PHP Code..

Code: 
$post_thanks_count = $templater->render();
vB_Template::preRegister('thanks_postbit',array('post_thanks_count' => $post_thanks_count));
What this is supposed to be doing is registering the {vb:raw post_thanks_count} variable from 'thanks_postbit' template so I can display it in 'threadbit_display' template. But I'm doing something wrong.