There is a giveaway from Walmart, but you have to buy something from them then follow the instructions on the register slip. Then if you won, they would send you the card in the mail. The SMS is from a scammer. He will ask you for money up front and send nothing in return, or install malware on your phone to steal your identity. The link in the SMS doesn't look like it came from Walmart-I wouldn't trust it. Do not reply, just delete it.