https://www.google.com/search?q=define%3Aprofessional&oq=define%3Aprofess ional&aqs=chrome..69i57j69i58j69i59.3223j0j7&sourc eid=chrome&espv=210&es_sm=122&ie=UTF-8#es_sm=122&espv=210&q=define:profession&safe=off
-a paid occupation, esp. one that involves prolonged training and a formal qualification.
Search define:profession. Poker players get paid, therefore they are professional.
Edit: I reread your original post, using your dictionary, no you aren't since you're not paid a salary since it's not a fixed amount.
The word has multiple correct meanings.
Same with amateur. If you have a dictionary that uses "a person considered contemptibly inept at a particular activity" as the definition, then you're not an amateur if you're crushing or beating your limit. If the definition is not a professional, then you would be an amateur.
All in all, it doesn't matter. You don't get any benefit by calling your self a professional poker player.
It's like a forum rank, CardsChat Regular. If we used CC's definition, it just means you have posted a certain number of posts. If we defined regular as happening often, then someone with 10k posts who doesn't visit the forum anymore wouldn't be a regular.