A fiat-to-crypto payment gateway is a solution that allows merchants to accept payments in traditional fiat currencies, such as USD or EUR, convert fiat revenue into cryptocurrency, and withdraw it to an external wallet.
However, most merchants prefer to do the opposite: accept payments in cryptocurrency via a crypto payment gateway (such as Cryptoprocessing by CoinsPaid), convert crypto into fiat, and withdraw it to a bank account. This is a safer and easier option from the point of view of accounting and taxation.