Then, you need a firewire to Thunderbolt adapter. Apple sells this cable. Then you need a thunderbolt 2 to thunderbolt 3 adapter, which works for any computer with USB-C input. Resources ...

From HDMI connectors and FireWire 400 or 800 cables to most standard USB ones and 30-pin dock connectors (the ones that also come bundled with a new iOS device), these cables have one thing in common: ...