There is a simple example in the project. I don't tested this with more complex variables.

Config: https://github.com/camunda-community-hub/camunda-dmn-tester/blob/master/server/src/test/resources/dmn-configs/dynamicOutputDmn.conf

DMN: https://github.com/camunda-community-hub/camunda-dmn-tester/blob/master/server/src/test/resources/dynamicOutput.dmn

I hope this helps. If it does not work please create an issue on Github with an example DMN.