Creates the {donor_title} tag for the GiveWP PDF Receipt

custom_pdf_tag_donor_title.php

<?php
function custom_pdf_tag_donor_title( $template_content, $args ) {	
	$donor_title  = isset( $args['buyer_info']['title'] ) && $args['buyer_info']['title'] !== '' ? $args['buyer_info']['title'] : __('', 'give');
	$template_content = str_replace( '{donor_title}', $donor_title, $template_content );
	return $template_content;
}

add_filter( 'give_pdf_compiled_template_content', 'custom_pdf_tag_donor_title', 999, 2 );