I'm gonna guess that "Ruby" is an expensive place, you took her to a cheaper place and paid for all of it then probably paid for her movie ticket as well. Let's analyze this!
What have you proved to her? By paying for her meal and her movie ticket you proved you are willing to pay for her stuff. Now considering you wanted to take her to a more exclusive restaurant and you are probably extremely gullible and ignorant, she has now figured she can (ab)use you. She knows you pay, she knows you're an AFC and since you said you would take her to that place and you didn't, she has figured you owe her that.
So, solution time. You've put yourself in a sticky situation, there's theoretically a chance for you to get this working. Realistically however this chance is slim to none considering your unrefined way of handling dilemmas. So I'm going to make it a choice for you, not one solution but two. There's the hard way, which is to go on that date and whatever happens will not end well for you. It's hard because you will somewhere down the road realize how royally you fvcked up and cry in sheer pain. Then there's the easy way, heed my advice and never talk to this chick again. It's easy because you save yourself the trouble, the pain and the money, but you'll not truly know why I'm giving you this advice.
I recommend the hard way, because not until you (in particular) have dragged yourself through the sh!t will you learn. Then you will understand why we act the way we do, why we rep you badly and why we give you this type of advice.
So yeah, enjoy your date with a gold digger. Don't make a thread about how to get her to pay, even though I know you will regardless of me saying this. Go out and fvck up, it's good for you