Reactive.jl which Escher depends on for interaction was entirely inspired by Elm! I think the main difference between Elm is that Elm is currently a client-only compile-to-JS language. Escher, otoh runs on the server and compiles to Virtual DOM instead of JS. The Virtual DOM can include custom HTML elements, I use Polymer extensively, and have a few elements of my own for doing things like event capture, websocket communication, sampling events etc.
They don't appear to be related. The previous discussion was about replicating an Escher style drawing in Julia. This is about a web framework for Julia that just happens to be named Escher :)