"The more you (will) ask them, the harder it will be"

Solution 1:

Will in that context is definitely not idiomatic, to the extent that it is, in fact, incorrect. In that construction, the first clause is always in the present tense because it brings the action into the present and then examines the probable consequences.

The more you ask them, the harder it will be.
The more you ask them, the less likely they are to do it.
The more you learn, the more there is to forget.

Edit

I suppose I should add for completeness that the first clause can be in the past tense if you are reporting what has already happened, and its consequences. Because the consequences became apparent at the time, the second clause is in the past tense too:

The more we asked them, the harder it became.
The more we asked them, the less likely they were to do it.
The more we learned, the more there was to forget.