Hello everyone,
Right now there is no active way to earn Overwatch League tokens for free right now as the Overwatch League is currently in off-season. Please note watching Overwatch World Cup matches, or any other Overwatch Esports events running right now DO NOT count toward earning league tokens or any other Overwatch League streaming rewards.
You can of course purchase Overwatch League tokens in the Blizzard Battle.net Store (PC), the PlayStation Store (PS4), or the Microsoft Marketplace (Xbox One).
Regular season matches for the Overwatch League 2018-2019 season will begin next February. Learn more at www.overwatchleague.com. To learn more about how earning OWL tokens works and any troubleshooting with earning them, check out my guide here on the forums.