The article was published by a satirical website called 'The Onion' and the claim is untrue.
On January 12, 2021, satirical website 'The Onion' published an article reporting that President-elect Joe Biden "died of a heart attack six days ago." According to the story, Democrats are reluctant to share the story that Biden died of a heart attack six days ago, especially in the wake of the recent US Capitol storming, and Senate Democratic leader Chuck Schumer is contemplating whether he should at least tell Biden’s family.
The site is a satirical website known for publishing untrue stories. Media Bias/Fact Check describes The Onion as "a satire website."