Can the coordinating conjunction 'yet' follow a subordinating conjunction?

Solution 1:

This is archaic but poetic. It's an example of an anapaestic tetrameter (although it really needs another unstressed syllable right at the start) — four feet of "da da DUM":

But although it is early, yet still I must rise.

As @crisis said, it's redundant, but redundancy can be employed for particular effect, as here.

Solution 2:

I'd argue the problem with the sentence "Although it is early, yet still I must rise" is that "although" and "yet" are redundant. Both imply a contradiction, so only one should be necessary.

Consequently, I'd use either "Although it is early, I must still rise", or "It is early, yet still I must rise".