There is no IP forwarding.
https://github.com/Whonix/ipv4-forward-disable
Tor is running on the gateway. It opens ports. The workstation can talk to these directly. (socksified)
System default traffic from the workstation (non-socksified), called transparent proxying, is redirected by whonix-gw-firewall to Tor’s DnsPort and Tor’s TransPort.
Whonix (previously called TorBOX) was based on TransparentProxy · Wiki · Legacy / Trac · GitLab. That’s how it all started.
No, static networking.