How to use 多ければ多いほど

Ahhhh.... so many coffee beans 

人が多ければ多いほどにぎやかだ。

The more the people, the noisier it is. 

酒を飲めば飲むほど酔いやすくなる。

The more you drink, the easier it is to get drunk.

So, here we encounter the verb+ suppositional(conditional) + verb(plain form) + ほど 

and yes, the verb can be replaced with the adjective. 

It’s used to create a condition of comparison. 

The two aspects of comparisons are the plain adjective/verb (多い・飲む） and the comparative adjective/verb. 

So, in the first example, you would be comparing the state of more people compared with just people and what that would result in. 

It’s also used more as a fact/statement which is usually neutral(without much feelings involved although that may not always be the case) 

Perhaps if you wanted to put more emotion, 人が多いとにぎやかだね。

人が多くいるとにぎやかだなあ might be preferred. I mean, this works well when you go to a restaurant and find loads of people and want to show some surprise towards the situation to your friend. 

But then again, one could also just say 人が多ければ多いほどにぎやかだなあ。

So it’s a little difficult to say which is used more often. 

As I always repeat, the best way to get a feel for this is listen to live Japanese conversations ( preferably when you are together with your Japanese friends ). 

速ければ速いほど世界記録に近づく。

The faster you are, the closer you get to the world record. 

雨が降れば降るほど土が弱くなる。

The more the rainfall, the weaker the soil gets(the looser the soil)