is there any command we can use to export the arp cache in the cisco 6509 switch to TFTP server
It depend on version of your device. In newer version you can do it by:
sh ip arp vrf | redirect tftp:
sh arp | redirect tftp:
for oldest version you need to write tcl script which will be copy output of "sh arp" in local file and then copy this file to tftp sever.
But simplest way is to get arp table by SNMP.