I have a spa and runs on 220, the breaker is 140 ft. from the spa what gage wire do I use/ should I use a gfci circuit breaker 50 amp (spa panel) do I run 4 wires with this unit or do I use aquick disconect and use only 3 wires what's the diffenence and what is safer

This feeder for a hot tub requires a 4 wire that will include an equipment ground. Along with two hots and a neutral.

For a 50 amp circuit at 140 feet, I would use #4 copper or #2 aluminum to reduce voltage drop.

The hot tub circuit requires a GFI circuit breaker someplace, either at the panel, or at the hot tub. There must be a disconnect at the tub, no closer than five feet away from the tub, this is where usually a GFI breaker is installed. If outdoors the GFI breaker enclosure must be rated NEMA 3R RainTight.