The pattern is something like:
- どうXならばYというのだ(か)
- What/How (much)/... on earth does one X to Y?
meaning
- Whatever/However (much)/... one does X, Y won't happen/is impossible.
More practically, X can be dropped from translation and just How is it possible Y would convey the meaning. Note that どうしたら="how" has essentially the same structure (literally how does one do to..).
Explanation by examples:
どうあがけば人間が雷に勝てるというのだ
How much must one struggle to defeat thunder?
How on earth can one defeat thunder?
どう見たらこれが猫だと思うのだ
What do you see to think that this is a cat?
How come you think this is a cat?
I think your confusion stems from the fact that there is no construction in English which naturally combines how and if, which is what どう・・ば does.
I'm not sure how much this helps, but see the following comparisons.
which literally translates to
- If one does this, one can beat thunder.
Now changing こう to どう and adding というのだ, it becomes (literally)
- If one does how/what, can one beat thunder?
Slightly more naturally,
- Can one beat thunder by doing what?
In the case of the sentence in question, a similar translation is
- Can one beat thunder by struggling how?