划分句子成分”what he said doesn't metter

matter!Not metter.
What he said (主语,由一个以what引导的主语从句充当) doesn't (助动词否定) matter (不及物动词充当谓语).他所说的不重要(或什么都不是).
整句相当于:It doesn't matter.只不过是What he said 代替了It.
弄句难点的:She has been there for everthing that ever mattered.(重要的时刻,她一直在我的左右)(发生重要事情的时候,她一直都在).
She (主语) has been (谓语,现在完成时,强调一直) there (地点状语) {for everthing that ever mattered} (表目的,状语).

what he said 是主语，这个主语是由一个从句来充当的，我们叫它主语从句。在主语从句中，what既起到连接作用，又在从句中充当主语。

"what he said "是主语，doesn't助动词的否定形式，matter是谓语动词。

what he said 是主语从句。