To reproduce, create a table like this:

<?php
$table = $this->getHelperSet()->get('table');
$table->setHeaders(array('Ф'));
$table->setRows(array(array('11111')));
$table->render($output);

result:

+-------+
| Ф    |
+-------+
| 11111 |
+-------+

The problem is in using str_pad() function in method renderCell().
The function does not work correctly with multi-byte strings.