Can I add text to a form file upload field?
You can add a #prefix to a file upload field using hook_form_alter, but I don't think it will give you what you're looking for

function test_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  if ($form_id == 'test_node_form') {  //custom content type of 'test'
    //custom field in the content type called 'field_test_upload'
    $form['field_test_upload']['#prefix'] = '&lt;p&gt;test prefix&lt;/p&gt;';
  }
}


With the above code I have a custom content type of "test" and a custom field called "field_test_upload"

When adding a #prefix to the field I get the following results: