function ИМЯТЕМЫ_preprocess_views_view_table(&$vars) {
  $view = $vars['view'];
  if ($view->name == 'myview') { // если для всех видов, то это условие убрать
    $vars['ad'] = array(
      5 => 'реклама 1', // вывод рекламы после 5-й строки
      10 => 'реклама 2', // после 10-й
    );
  }
}

<?php
// $Id: views-view-table.tpl.php,v 1.8 2009/01/28 00:43:43 merlinofchaos Exp $
/**
 * @file views-view-table.tpl.php
 * Template to display a view as a table.
 *
 * - $title : The title of this group of rows.  May be empty.
 * - $header: An array of header labels keyed by field id.
 * - $fields: An array of CSS IDs to use for each field id.
 * - $class: A class or classes to apply to the table, based on settings.
 * - $row_classes: An array of classes to apply to each row, indexed by row
 *   number. This matches the index in $rows.
 * - $rows: An array of row items. Each row is an array of content.
 *   $rows are keyed by row number, fields within rows are keyed by field ID.
 * @ingroup views_templates
 */
$n = 0;
$total = count($rows);
?>
<table class="<?php print $class; ?>">
  <?php if (!empty($title)) : ?>
    <caption><?php print $title; ?></caption>
  <?php endif; ?>
  <thead>
    <tr>
      <?php foreach ($header as $field => $label): ?>
        <th class="views-field views-field-<?php print $fields[$field]; ?>">
          <?php print $label; ?>
        </th>
      <?php endforeach; ?>
    </tr>
  </thead>
  <tbody>
    <?php foreach ($rows as $count => $row): ?>
      <?php if (isset($ad[$count])): ?>
        <tr class="<?php print implode(' ', $row_classes[$n]);?>"><td <? print 'colspan="'. count($row).'"'; ?>><?php print $ad[$count]; ?></td></tr>
        <?php
        $row_classes[$total] = array(($total % 2 == 0) ? 'odd' : 'even', 'views-row-last');
        $row_classes[$total-1] = array((($total-1) % 2 == 0) ? 'odd' : 'even');
        $total++;
        $n++;
        ?>
      <?php endif; ?>
      <tr class="<?php print implode(' ', $row_classes[$n]); ?>">
        <?php foreach ($row as $field => $content): ?>
          <td class="views-field views-field-<?php print $fields[$field]; ?>">
            <?php print $content; ?>
          </td>
        <?php endforeach; ?>
      </tr>
      <?php $n++; ?>
    <?php endforeach; ?>
  </tbody>
</table>