Their page never specifies a "discount" rate and only show the 10% remittance rate. This makes their example table at the bottom near fraudulent because the "daily revenue" column is already discounted. I'd bet their discount rate is the same ~13% it was six months ago [src].
They know your revenue history, so I expect they're offering something which will likely take you 9-12months to pay back at the remittance rate (10%) based on your projected revenue. Note since this isn't a loan, if you pay it back early by growing revenue, Shopify still makes the same returns (13% discount rate) on their capital. Good deal for them, likely comparable to credit card rates for businesses, but since it's cash it's more flexible (pay employees, payoff loans, brides, etc).
[src]: https://twitter.com/seobrock/status/669269206584553473