Yes you can eat expired cake.
As long as the expired cake has no mold on it or any other really bad taste or smell to it then it's safe to eat the expired cake.
Expiration dates on cakes does not mean that the cake is actually bad or unsafe to eat.
Although when a cake expires it usually becomes stale and not as good to eat.
But it's still safe to consume an expired cake as long as there's no mold on the cake.
A cake should be kept refrigerated or frozen until you're ready to serve it or eat it if you're not gonna serve the cake or eat the cake within a day or two.
Also expired cake mix is safe to bake with and eat as it does not mean it's bad.
I've eaten expired cake and have baked with expired cake mix that had been expired for a year and the cake mix was still okay to eat.