All of their broths and meats (excluding things like imitation crab, meatballs, etc) are gluten free to my knowledge. Not all of the ingredients to add into your pot are but any fresh vegetables and tofu should be fine. I have celiac and have eaten here multiple times and felt fine. Plus, it's delicious :)
Editing review to clarify: most of the staff is not knowledgeable about gluten, and you'll need to use your own best judgement to eat here. There are many things with obvious gluten in them (all appetizers, fish balls, wheat noodles), but things that should be gluten-free, like the broths, meats, and vegetables, are.
I came here because of the other review but ended up leaving immediately. Two different waitresses and a manager all seemed not to know what gluten is. They put out several appetizers, including spring rolls and something else which looked breaded, and we asked which are gluten free. They immediately started talking about not being sure if the sauce on top of the rolls was gluten free: when we pointed out that spring rolls themselves aren't usually gluten free, they were like "oh yeah". They also said they'd do their best but we needed to watch out. And the ingredients to go into the hot pot are all from an open buffet which includes some glutenous noodles. They were very polite and understanding when we said we had to leave.