View difference between Paste ID: iaGjrpg0 and FpprZ9p9

 <?php
 // http://www.gravityhelp.com/forums/topic/automatic-sign-up-page-generating-a-new-web-page-or-post#post-179371
 // the 10 (priority), 2 (arguments) is documented here http://codex.wordpress.org/Function_Reference/add_filter
 // change the 5 here to your form ID
 add_action('gform_after_submission_5', 'update_page_settings', 10, 2);
 function update_page_settings($entry, $form){
 
 	// get the post
 	$post = get_post($entry['post_id']);
 
 	// create a page, not a post
 	$post->post_type = 'page';
 
 	// set the page template
-	update_post_meta($post_id, '_wp_page_template', 'template-my-form.php');
+	update_post_meta($post->ID, '_wp_page_template', 'template-my-form.php');
 
 	// update the post
 	wp_update_post($post);
 }