Does Batman gates of gotham tie in to the new 52? I know it was made right around the time flashpoint happened and right before the new 52 started yet it was written by Scott Snyder who wrote the new 52 batman series.
It doesn’t tie-in in any narrative way. It takes place before the actual reboot, and features characters portrayed as they’d been before Flashpoint.
But, it does present something of a canonical quandary: the Architect, who was introduced in Gates of Gotham, did appear after/during the New52 (for example, in Batman: Eternal), and he seemed to have the same basic motives and backstory. However, Cassandra Cain didn’t exist for a while, yet she appeared as Black Bat in GoG.
Comics stories are typically planned out months in advance, from what I understand, so chances are Snyder was working on this just before plans were in motion to reset the universe.