From The Revue website:

From January 18, 2023, it will no longer be possible to access your Revue account. On that date, Revue will shut down and all data will be deleted. This has been a hard decision because we know Revue has a passionate user base, made up of people like you.

In the meantime, you will be able to download your subscriber list, past newsletter issues, and analytics by following the instructions here.

If you run a paid newsletter, on December 20, 2022 we will set all paid subscriptions to cancel at the end of their billing cycle. This is to prevent your subscribers being charged for Revue content after the point where it is no longer possible to send newsletters from Revue.

We want to remind you that it is your responsibility to adhere to any applicable laws, rules and regulations in connection with your subscriber list and other data we share with you, and Twitter, Inc. has not obtained permission for you to use subscriber information for any purpose.

We’re grateful to everyone who has used our service over the years, and hope we can continue to help you build a community with your readers on Twitter.