With the WP1099 plugin, you can view payouts made to each vendor or affiliate during the year.
Simply click on WP1099 in the left side menu, then click the Payouts tab at the top.
This page will show you each vendor who has reached the applicable minimum payout threshold, with the total of all the payouts made to them for the current tax year.
Payout amounts listed are for the tax year selected in the WP1099 Settings. If you wish to view a different tax year, click the Settings tab, choose a different tax year, and click Save Changes. This will update the amounts shown on the Payouts tab with the correct year's payments.
If you are using more than one of the compatible plugins along with WP1099, you will see a link at the top of the Payouts tab for each plugin. Click on that link to see the results separated by payouts in that plugin.