I have always known that I will/would

Either works.

Why do you believe that 'will' is "in line" with 'have [---] known', Ms Tan?

Both refer to present, whereas 'would' is the past form.

A native speaker, Ceili, told you that both would work, Ms Tan. Shouldn't that make you pause for a moment to wonder whether what you wrote, above, is accurate?

Note the two underlined modals in my reply, above. Both are purported to be "past forms" and yet both describe a future, the first a more general future, meaning "at any time, in such a situation" and the second, in a specific, though tentative suggestion as to what you might want to consider. Four words back from the start of this sentence is another purported past form modal, 'might', working, again, in a future sense.

I'll leave it up to you but I beg you, please don't simply let this die. Modal verbs are extremely, VITALLY important in understanding the English language and you are operating under a serious misconception that has to drastically affect your ability to understand much of the English you encounter.

There is a second misconception that you seem to operating under and that is that tenses have to match, that English has Tense Concord/Sequence of Tenses/Tense Agreement. Such is DEFINITELY NOT the case for English. As the Cambridge Grammar of the English Language notes, and I paraphrase, as my copy is not at hand, there are no rules specific to tense agreement in English.