Hi,
There are several ways to go about it.
The best is to have HikaMarket Multivendor and one vendor per publisher ans assign each product to its vendor. That way, you can easily see the sales of each vendor and they can even connect to your website to look at them themselves if you allow them that. That way, it's all automated for you.
An alternative is to create one unpbulished category per publisher and add the publisher category to each product as a second category. Then, with the report tool (menu Orders>Reports) you can create one report per publisher and restrict the report to only the category of the publisher. It's a bit more work but that should give you what you need too.