Use the wires that comes with the motors. As for other wires, I tend to use 12AWG from the power distribution board to the ESCs and 10AWG from the batteries to the power distribution board (especially if only using one battery which I wouldn't recommend- use two). This might be overkill depending on the mass you are intending to lift but big octos tend to be big bucks so I like a bit of head room. As for the PDB I would go for 200A minimum. Again it depends on the mass you are hopping to fly. Another way to look at it is that those motors will probably draw a max of 30A (based on the Tarrot 4114-320) so with all motors at max chat, that's 240A not that you would ever draw that current but it would give you an idea. I am currently flying a rig at 20kg and its current draw whilst hovering is in the 160-180A range.
Another way to look at it is look at the wires on the components you have got and match them. For example, if your ESC uses 14AWG between it and the power supply then use 14AWG. It's kind of pointless going thicker as the bottleneck, for want of a better expression, will be the thinner wire.
