In Shakespeare's Macbeth, Macbeth is influenced by the witches and his wife. But while it is obvious that he is influenced, he certainly bears responsibility for much if not all of what he does.
The witches and Lady Macbeth don't actually do anything. Macbeth does it all. He kills Duncan, then shuts his wife out of the decision-making process, then orders a killing spree.
He gets the idea of being king from the witches, is talked into going ahead with the assassination by Lady Macbeth, and gets reassurance from the witches the second time he meets with them (remember that he seeks them out this second time). But he's the one who does the killing. He is very much responsible for his actions.
By the way, though, a more ambiguous question than the one you ask, and a question that is more difficult to answer, is the question of the role of fate in Macbeth's actions, rather than the role of influence by others in the play. The issues are related, yet different. But that is for another question.
One of the advantages of watching a play or reading as book is that audiences or readers form opinions of their own. Over the centuries, Macbeth's accountability in Macbeth and Shakesperare's intent have been discussed at length. A modern audience may feel that Macbeth is answerable for his actions as the notion of the noble soldier has dramatically changed with time. They would not feel sorry for a man who cannot be "so much more the man" (I.vii.51) except through deceit and murder.
Macbeth starts scheming right from the start as the witches reveal the possible extent of his future rise to king. He is faced with a similar future as Banquo and yet his actions are very different. Banquo even wonders " "Good sir, why do you start, and seem to fear things that do sound so fair?" ((I.iii.51) The witches have been proven right in the first context of the Thane of Cawdor, so why not wait for the next, natural event. Banquo even warns Macbeth of "the instruments of darkness."(I.iii.124)
Although stereotypes do still exist, in Shakespeare's day, they abounded and we see Lady Macbeth breaking with stereotypes in her efforts to "unsex" herself but at the same time conflicted by her need to nurture her husband and "Partner of Greatness"(I.v.10) such as Macbeth calls her. This reversal of gender roles could have confused Macbeth but, as the previously valiant, courageous soldier, he later has no difficulty reaching past this as he continues on his killing spree having successfully killed Duncan. He uses his position of power to commit the most heinous deeds. It is his fear of discovery that sends him into a madness that cannot be described or recognized, under the false belief that "none of woman born shall harm" him.(IV.i.80)
Therefore some will argue that he is responsible for his own downfall due to his own schemes and refusal to keep his ambition in check.
In the play "Macbeth" by William Shakespeare, the author shows the flaws, failings and deficiencies in Macbeth's character. One thing that makes him easily influenced by the words of others is his suggestibility. He has a personality that is easily directed by outside stimuli - in this case the "weird sisters" or witches. The question is whether we can actually 'blame' people for the personalities they are born with or inherit. They may be stuck with failings or attributes such as moral weakness, cowardice, greed or ambition. One could maybe expect that Macbeth could fight harder against his impulses and drives for contol, power and ambition. All the witches do to influence his actions is to plant a spark - Macbeth himself fans the flame. Whether he,or his genes, are responsible for the attention he gives to the influence of the witches is open to question.
In the play "Macbeth," both the witches and Lady Macbeth were responsible for Macbeth's downfall. Macbeth was at first a noble, loyal man who would never harm his king. However, the witches' foretelling gave Macbeth greater ambition and desire to become king himself, and Lady Macbeth's manipulation and insistence led him to commit the murders needed to fulfill this heightened ambition. Macbeth is resposible for his own downfall because his human nature, the witches prophecies and Lady Macbeths persuasions also play a part in Macbeth's downfall.