Access $display_submitted in page template
While normally done in node.tpl.php, if the page is a node view page, the $node variable is also available in page.tpl.php

You can then use something like:

if (isset($node)) {
  // Check if display submitted variable is set for this node type
  if (variable_get('node_submitted_'. $node-&gt;type, 0)) {
    // Do stuff
  }
}


An alternative approach would be adding the required logic instead to an implementation of

hook_preprocess_page

Bonus update: You can see the $node variable added to page.tpl.php in core template_preprocess_page

if ($node = menu_get_object()) {
  $variables['node'] = $node;
}