She is difficult to beat as she will give you most important item in the game when you later meet her.
I beat her, here's how you do it. Do the minimum bet and no matter what. Always stick to the minimum bet. The goal is to slowly drain her. If you do it this way. You will guarantee win.
Do keep in mind this is RNG, it took me only twice to beat her after I realized she folds as soon as you have a good hand.
This method took me maybe 15 to 20 minutes, can't remember it's been awhile.