Site up for me.
They’ve been finicky with massive influx of people. They can’t get funding by VISA payments either, so only mail by checks for the premium service, or e-checks.
If they can’t accept credit cards they are not ready for prime time.
Try it again. I get a 'no such domain' error when I try gab.com.
Looks like Gab's been booted from their DNS provider.