I looked up this years event. It seems to be the same as lat year.
You will be given some chips as part of your ticket price. You can purchase more too. They have slot machines, poker tables, blackjack tables, and maybe roulette and/or craps. I am not sure what you win or how any of that works. I grew up in Northern CA, and my dad went to Reno, NV at least 2 times a month. I was dragged along from about 7 years old onward. So I have no desire to do the casino thing. My wife and some of her co-workers played slots and blackjack. They came back empty handed but had fun.
The Texas Unlimited Band plays a variety of music and does a good job.
Standard attire - I wore nice, my fancy boots, a button up shirt and a sport coat. I think I wore a tie but cannot remember 100%. This was the most common dress. Some people were in suits, but jeans and a sports coat was common with the guys. It was about equal numbers of those with or without a tie.
It wasn't that stuffy and overall a good date night.