In recent times, poker has experienced a surprising and radical shift away from the clichéd old image of dodgy back rooms and smoky saloons. Today, the answer to your question is: Not many poker rooms allow smoking and no poker rooms on the Strip allow it.
Here's the current list of poker rooms in Las Vegas that do allow smoking:
For further details about these rooms and all the non-smoking rooms in town, click here to visit our full list of non-smoking Las Vegas poker rooms.