I have been to many Indian restaurants but the vegan options are not always that positive -- even at the vegetarian restaurants. Gateway takes this seriously as I believe one of the owners is also a vegan. Everything vegan-friendly is well- marked. If there is something that you want that may be vegetarian but not vegan, they will modify it for you. They do use the same fryer for all foods so be conscious of that. They may be able to bake some options instead of frying if you want and they are available to do so.
The food is also really good quality. There is always a large wait staff to help and check on you and always friendly.