I need to know what type of wire to use for wiring a 220v hot tub. The breaker box is in the house, the wire will come through a concrete wall.

Wait, you also need a 50 amp GFI breaker added to your box or to a sub panel. You may get away with #10 wire but I'd go #8 not knowing your hot tub. Have fun drilling through that concrete wall. Any chance of getting higher and drill the plate?

Would it be best to wire it directly to the breaker? Or to create a 220 plug-in, like the dryer?

Wire directly to the GFI. They are bigger than normal breakers so you may need to add a smaller sub pnale.

What you need to do is post the power the spa is rated for, amps or watts. Then wait until tkrussel answers. He won't post an answer you could interpret as saying you could connect a 50 amp breaker to # 10 wire. The rating of the breaker and the wire must both exceed the draw of the spa.

Most hot tubs need a 50 amp circuit, using a 50 amp GFI breaker and #6 copper wire if using Romex cable. #8 or #10 Romex will not be sufficient, and cannot be connected to a 50 amp breaker.

Get back with the electrical data listed on the nameplate, and the type of wiring method to learn the proper wire size.