How to replace current symbols with font awesome icons in every pager?
If you look at function theme_pager you see this line:

 $li_last = theme('pager_last', array('text' =&gt; (isset($tags[4]) ? $tags[4] : t('last »')), 'element' =&gt; $element, 'parameters' =&gt; $parameters));


which eventually leads you via theme_pager_last to function theme_pager_link which has this bit of code:

return '&lt;a' . drupal_attributes($attributes) . '&gt;' . check_plain($text) . '&lt;/a&gt;';


where check_plain is the function that converts html to text.

so you need to supply your own version of theme_pager_link. Look at this post and others for information on how to do that:

How to override theme functions in Drupal 7