If your game earns anything, it will be shown on your dashboard both under earnings and in the top summary.
You only need to complete the Tax Interview once you qualify for a pay out.
When you request a pay out, support will most likely activate the function on your dashboard and let you know .
You can only request a pay out when the amount you will receive equals $5 or more.
You'll qualify for a pay out probably once you receive about $10-$12 the first time because itch.io's cut, payment processor, and the one-off tax interview fees are deducted.
On future pay outs, only itch.io's cut and the payment processor fees are deducted.