I don't think there's a way to do this using Tableau directly. There are a number of tools (import.io being a popular one) that help you extract data from the website to a data set that can then be uploaded to Tableau. However, this won't be automatic (i.e. you would need to manually refresh the data set on whatever cadence you desire).
There are also ways to write some simple software to pull the data into a database that can be used by tableau, but that will be rather tricky unless you have some dev background.