IPhone 5S vs iPhone SE?

Is the iPhone SE worth paying the extra $30 over the iPhone 5S? How long will the iPhone 5S still be supported by Apple?

I would go for the SE. If I remember correctly, the SE has pretty much the hardware that the iPhone 6S (I think), just in a smaller size. That is significantly newer and faster than the 5s' archaic (relatively speaking) 2013 technology.

As for how long it will be supported, I'm not sure. It is nearly 5 years old.

But the SE will be a much better buy. It will be a lot faster and still be supported for years.

The SE is basically a 6s in a 5s body. So for that reason alone, yes it is worth it.
As far as software updates, the 5s should stop getting them later this year, though there are reports lately that it may get those updates until that time in 2019.