Can I turn off advertising without reducing my sales?

Currently I spend $12/day on advertising. It’s resulting in some ad sales, but I’m barely generating any returns on my ad spending, when you take into consideration fulfillment fees and other fees that Amazon takes.

Lately, roughly half of my sales are generated from ads, and the other half is organic.

If I turn off (or dramatically reduce) my ad spending, will I suffer from a significant decrease in my volume sold? Alternatively, is there any merit in dramatically INCREASING my ad spending for a few weeks, which hopefully will cause an increase in organic sales (due to a higher ranking), and then bringing my ad spending back to its current level (or turned off entirely)?

Thank you!