Hi Meredith!
You certainly may choose to load your planned dining expense budget onto a Disney Gift Card.
In fact, that's precisely what I choose to do when my family visits without a Dining Plan. It keeps us 'on budget' somewhat, is safer than carrying cash around, and keeps you from racking up a high room charges tab if you're trying to stick to a daily spending plan. You'll have no problem using the gift card at Snack Carts, Quick Service Dining locations, Table Service Dining and even in the shops. It's perfect!
If you wish, you can
purchase Disney Gift Cards online prior to your arrival at Walt Disney World. Personally, I just visit the Gift Shop in my Walt Disney World Resort with cash I've brought from home, and have it loaded onto 1 or more gift cards. I lock up the one(s) we don't need right away in our in-room safe and just take one with us daily. Each time you spend from the card, you'll receive a receipt that shows the amount remaining on the Gift Card.
My kids also bring along their spending money from home and load it onto a Disney Gift Card that they pick out. There are so many fun designs to choose from!
Thanks for visiting the Disney Parks Moms Panel with your question. If you have additional inquiries prior to your trip, I hope you'll write me back. I'd love to hear from you again!
Wishing you a simply Magical time preparing for your next trip to Walt Disney World Meredith!
Kirsten