Lonely Planet says the Katmandu airport officials accept “any major currency” but land borders only accept USD.
The official site says:
While you can use different modes of payments (at visa fees collection counter), we advise
you to carry some cash to be on the safe side.
This site is a bit more dubious but claims “Euro, Swiss Franc, Pound Sterling, US Dollar, Australian Dollar, Canadian Dollar, Hong Kong Dollar, Singapore Dollar and Japanese Yen”.
Since you have none of those currencies (perhaps the fact Chinese don’t have to pay for the visa means they don’t accept CNY), and it appears credit card payment is probably not possible, at least not reliably, I would suggest carrying something like USD or maybe Euros since “tomorrow” is very close.