田中さんのミスを僕がフォローするんだから、労働に見合った報酬を受け取るのは当然だ。

、。

Since I'm the one covering for Tanaka's mistakes, it's only natural that I receive compensation proportional to the labor.

Literal

Tanaka-san [possessive-の] mistake [object-を] I [subject-が] covering [copula-んだから], labor [to-に] matching compensation [object-を] receiving [topic-は] natural [copula-だ].

ミスをフォローする uses the loan フォロー ('follow-up, covering for'). ~んだから ('since, given that') states the premise assertively. 労働に見合った報酬 ('compensation matching the labor') uses 見合う ('to match, to correspond'). 当然だ ('it's natural, it's only right') asserts the fairness of the claim. The speaker is making a frank argument about fair pay for extra work.