How to pass a value from one interface on button/richtext click to another interface rule input ?

What is the relationship between the two interfaces in question?  The standard way to do this sort of thing is via a Process Model, in which case this use case is standard practice, and very easy.

it dependes how and what excatly you want to archive:
1.) you can call the other form(component) by rule!myFormComponent() in your main form.
you can use the rule inputs like usual: rule!MyInterface(ruleinput1: "abc", ruleinput2: 123)
2.) or like mike suggested via process.
submitting your form and providing the values or your rule inputs towards the process and using the pv(s) to update the rulesinputes fo your new form.