Are you trying to create array in PHP? Then:
PHP
$smarty->assign('cid', array(69,68,27,31,70,71,72,73,74,75,76,77));
Smarty
{ if !in_array($productgroup.gid, $cid) }
...
{/if}
Or you want add dynamic element in your array? Then:
PHP
$smarty->assign('cid', $some_number);
Smarty
{ if !in_array($productgroup.gid,array(69,68,27,31,70,71,72,73,74,75,76,77,$cid)) }
...
{/if}