Your paths should be:
/wp-content/themes/gt3-wp-pure/page-templates/
… instead of:
public_html/wp-content/themes/gt3-wp-pure/page-templates/
Your paths should be:
/wp-content/themes/gt3-wp-pure/page-templates/
… instead of:
public_html/wp-content/themes/gt3-wp-pure/page-templates/