They have a "Reopen Closed Tab" action you can map in Settings -> Keymap. You can also use "Recent Locations" Ctrl-Shift-E to see recently touched files, the first one will be the one you just closed.

You can use Ctrl+E / Cmd E to invoke the `Recent Files` dialog -- the first file in the list will be the last closed tab.

https://blog.jetbrains.com/phpstorm/2013/02/navigating-betwe...

There is also the `Reopen Closed Tab` action, which it seems doesn't have assigned shortcut by default, but you can assign it to whatever you feel comfortable with.

To accomplish similar I use "Back" from the Navigate menu regularly and have it bound to cmd+opt+left arrow. Works pretty well - also puts your cursor back to where it was in that file.