The following code, when inserted into a custom plugin or your child theme’s functions.php file will forward all file uploads (images and documents) to your Media Library within your WordPress website. As originally seen on: https://infinitesynergysolutions.com/learning-center/add-gravity-forms-file-uploads-and-image-uploads-to-the-media-library/

media-library-upload-gravity-forms.php

<?php

// Uploading to the Media Library Using Gravity Forms
// https://endurtech.com/upload-to-the-media-library-using-gravity-forms/

add_action( 'gform_after_submission', 'iss_gf_after_submission', 10, 2 );
function iss_gf_after_submission( $entry, $form )
{
  // Walk through form fields, find file upload fields
  foreach( $form['fields'] as $field )
  {
    if( $field->type == 'fileupload' )
    {
      // See if file was submitted with entry
      if( isset( $entry[$field->id] ) )
      {
        $fileurl = $entry[$field->id];
        // ID of post this attachment is for. 0 for unattached
        $parent_post_id = 0;
        // Check type of file, for use as 'post_mime_type'
        $filetype = wp_check_filetype( basename( $fileurl ), null );
        // Path to upload directory
        $wp_upload_dir = wp_upload_dir();
        // Gravity Forms uses its own upload folder, get that location
        $parts = explode( 'uploads/', $entry[$field->id] );
        $filepath = $wp_upload_dir['basedir'].'/'.$parts[1];
        $fileurl = $wp_upload_dir['baseurl'].'/'.$parts[1];
        // Array of post data for attachment
        $attachment = array(
          'guid' => $fileurl,
          'post_mime_type' => $filetype['type'],
          'post_title' => preg_replace( '/\.[^.]+$/', '', basename( $fileurl ) ),
          'post_content' => '',
          'post_status' => 'inherit');
        // Insert attachment
        $attach_id = wp_insert_attachment( $attachment, $filepath, $parent_post_id );
        // Image manipulations are an admin side function. Gravity Forms is a frontend function, include image manipulations here.
        require_once( ABSPATH . 'wp-admin/includes/image.php' );
        // Generate metadata for attachment, update database
        if( $attach_data = wp_generate_attachment_metadata( $attach_id, $filepath ) )
        {
          wp_update_attachment_metadata( $attach_id, $attach_data );
        } else {
          echo '<div id="message" class="error"><h1>Failed to create Meta-Data</h1></div>';
        }
        wp_update_attachment_metadata( $attach_id, $attach_data );
      }
    }
  }
}