What are the High-level source current and the Low-level sink current of GPIO?

Hi everyone,
I’m trying to use UART communication from the ESP32 to ODrive. For an UART-Isolator with optocoupler 6N137 I need to know the High-level source current and the Low-level sink current for both GPIOs: UART_A.TX and UART_A.RX.
Thank you for helping.