Can I use an Identification Card instead of a Driver's License at the casinos in Las Vegas?

Sure you can. However, if you look too young to legally gamble you will be asked for a valid ID, if you cannot produce one you will be asked to leave the premises and you will forfeit any winnings you might have. If you are old enough and you are asked to produce a valid ID and you hit a jackpot that requires a 1099-G be filled out and you do not have a valid ID you will not be paid.