Time_pattern not working with helper

Configuration
2

Correct you can’t do that. If the documentation does not mention templates then you can’t use them.

You can do this:

trigger:
  - platform: template
    value_template: "{{ now().minute % states('input_number.licht_timeout') | int == 0 }}"

% is the modular arithmetic operator. So if the current minutes divided by your timeout leaves no remainder the trigger will fire. Same as the time pattern trigger you attempted.

Also in future please format your pasted config correctly for the forum. See: https://community.home-assistant.io/t/how-to-help-us-help-you-or-how-to-ask-a-good-question/114371#oneone-format-it-properly-16