Yes, there are now many Ethereum gambling casino sites that let you wager ETH and other cryptocurrencies. Some of these also support regular fiat currency. Because it’s sometimes difficult to recognize the fiat value of ETH, even when gambling with the crypto coin, your balance might be displayed in dollars or another fiat.
Laws do vary, but as long as online gambling is legal in the jurisdiction the casino is based and crypto is legal in your jurisdiction, all should be ok.