does IntelliJ IDEA support Kotlin Native now via Gradle or not?

I think it should

you could open project and run Gradle tasks, but IDE smartness, like refactoring and navigation not there. Recommended approach is to use CLion or AppCode K/N plugins.

I guess CLion is preferred over idea in this subject

but CLion still uses CMake as build model? I cannot see where I can import a Gradle project, or how to create a new Gradle based Kotlin Native project

There is a k/n plugin, to clion, I think it has a Gradle support

K/N plugin for CLion does not support gradle at the moment, but we are working on it.