So far, here are the ones supported. There could be more. Would request the community to update this list.
- Authorize.net (native)
- APS
- PayPal PayFlow
- Braintree
- WorldPay
- eBiz
- AcuCharge (Vantage Card)
- PayPal Request for Money (not a payment gateway, but a way to send email to customer and get money via their PayPal account)