>I'm using GTH transceiver for high speed transfer. I want to know if there is any way to correct error at the receiver end or resend data again.
Error correction and data re-transmit is not part of GTH PMA/PCS features. Please see also UG576. These features should be implemented in data-link protocol/layer (instead of PHY/Coding layer). (i.e: PCIe IP is implementing all these mechanisms in its module. It is not using GTH features )
>How transmission packet formation looks like in GTH transceiver?
It depends on your GTH configuration, whether your encoding/decoding configuration is using 8B/10B, 64B/66B, RAW (or other). Generate GTH example design and run simulation is a good method to find the answer.