Hello
Fungus gnats are a pain!
The best most effective treatment I've found is the granular "mosquito bites" they sell them everywhere, garden stores, home depot..Walmart. sprinkle it on soil, in any saucers under pots and most importantly soak some in a gallon of water overnight and water the soil thoroughly. It'll kill most of the larvae in there.
You can also do neem meal or cake and similar thing soak overnight and stir and then soak the soil.👍 problem should be solved or manageable. Keep the yellow sticky cards though right above the soil and that way it can catch any flying adults.