https://www.pcgamer.com/bioware-announces-an-anthem-demo-is-coming-in-february/

During a pre-panel press briefing at PAX West, Mark Darrah and Mike Gamble of BioWare announced that the VIP demo for Anthem will be arriving on February 1st for PC, Xbox One, and PS4 simultaneously. 

'VIP' because EA Access subscribers and anyone who preorders are the only ones guaranteed access, though more methods for having a go at the demo will be detailed at a later date. Gamble and Darrah said that this will not be a tech demo meant designed for testing online infrastructure, but a legitimate, old-school demo—a vertical slice of Anthem designed to demonstrate what it's all about.