Let's say the hot tub uses 30 amps @ 240. That is about 7.5KW. It would need 60 amps at 120, meaning bigger wires. But KV is KV.
At 12 volts, the battery would need to supply 600 amps.
The CCA rating of a battery is not meaningful here...that is a short term spec for the starter of a vehicle. The steady state draw is much less. You need to know the total KWH rating to know how long it would power the tub