Publishers affirm, represent, and warrant that they own or have the rights, licenses, permissions and consents necessary to publish, duplicate, and distribute the submitted content
The Company does not endorse copyright infringing activities or other intellectual property infringing activities and violations of may result in the removal of content if the Company is notified of such violations. Removal and termination of accounts may occur without prior notice.
Strictly speaking, you shouldn't upload anything that you don't have the rights to share.
But Itch doesn't do copyright checks, you can upload the game, but if someone claims the rights, they can take down the game or close your account, you have to be clear about that.
Be careful, just because a company closes doesn't mean that its products aren't actively protected, it often happens that another company buys the rights to those products.