In a similar way to どんなに～ても, いくら～でも is regularly translated to ‘no matter how (A), (B)’. However, unlike どんな (which is an abbreviation of どのような), いくら is a 名詞（めいし） that comes from the kanji 幾（いく）ら, meaning ‘how much’. When partnered with ても
(with verbs and い-Adjectives
), or でも (with nouns and な-Adjectives
), the literal meaning means ‘however much (A), (B)’.
With いくら～でも, the (B) part of the phrase will usually highlight something that is being negated, giving the phrase it's ‘no matter how much’ nuance.
No matter how much you tell him, he won't change.
No matter how new it is, of course it is going to break if you drop it!
No matter how much you dislike them, that is a hurtful thing to say.
No matter if it is me, I can't lift something that heavy. (Even if it is me, who is strong, I cant lift something that heavy)
Despite this trend of being used in sentences that contain ない or ありません, いくら～でも may also be seen in positive sentences. In these cases, despite not being negative, the (B) phrase will still be something that is surprising/unexpected in some way (due to its extent or amount).
I'll listen to you vent however much you need.
As for snacks, I have plenty, so take all you want!
幾（いく）ら places more emphasis on the ‘amount’ of something, while どんなに
places more emphasis on the ‘type’, or ‘style’. Due to this, いくら will be a better choice when the ‘volume’ of something is being highlighted, while どんなに
will sound more natural when the ‘state’ is being discussed.
I will pay however much for those shoes, so please let me have them! (Amount only)
I will pay whatever sort of money for those shoes, so please let me have them! (Possible amount or type. Dollar, yen, euro, etc)
Despite this small difference, いくら and どんなに
are used fairly interchangeably in most situations.