打ち出す in this case means "to create/come up with/etc". The subject of the sentence is 司馬遼太郎氏が, so the verb 打ち出す (to create) needs to match with it as the active form. [こうした評価に決定的な影響を与えてきたのは]、 作家の司馬遼太郎氏が小説「 坂の上の雲」 で打ち出した見方だ。 [What has decisively affected on this evaluation]; [it is] a point of view that an author, 司馬遼太郎 created in his novel 坂の上の雲. 司馬遼太郎氏によって打ち出された見方; in this case, the verb becomes the passive form. A point of view that was created by 司馬遼太郎. Hope this helps.