Is there anything in Apache's error_log? Is this mod_php or FastCGI or normal CGI PHP? What happens if you run the script via the command line?
You could also try setting PHP's error log and looking in there.
EDIT1: Try:
echo "before";
if(!function_exists('oci_connect')) die('Oracle Not Installed');
And post the results...
EDIT2: I'm really not sure. My best bet is this info from the PHP manual:
The most common problem with installing OCI8 is not having the Oracle environment correctly set. This typically appears as a problem using oci_connect() or oci_pconnect(). The error may be a PHP error such as Call to undefined function oci_connect(), an Oracle error such as ORA-12705, or even an Apache crash. Check the Apache log files for startup errors and see the sections above to resolve this problem.
Anyone else have any ideas to help out Bryan?