Yes, you can still get pregnant. The heat or chlorine in a hot tub will not kill sperm or make it more difficult for sperm to swim inside the vagina. Anytime semen gets inside the vagina or on the vulva—whether you are in a pool, hot tub, or romantic, candle-lit bedroom—you can get pregnant!
The good news is that you can’t get pregnant just from being in the water with semen, so unless you’re actually having penis-in-vagina sex in the water, you don’t have to worry about pregnancy.