It is the near-universal position of scholarship that the Gospel of Matthew is dependent upon the Gospel of Mark. This position is accepted whether one subscribes to the dominant Two-Source Hypothesis or instead prefers the Farrer-Goulder hypothesis.
It is also the consensus position that the evangelist was not the apostle Matthew. Such an idea is based on the second century statements of Papias and Irenaeus. As quoted by Eusebius in Hist. Eccl. 3.39, Papias states: "Matthew put together the oracles [of the Lord] in the Hebrew language, and each one interpreted them as best he could." In Adv. Haer. 3.1.1, Irenaeus says: "Matthew also issued a written Gospel among the Hebrews in their own dialect while Peter and Paul were preaching at Rome and laying the foundations of the church." We know that Irenaeus had read Papias, and it is most likely that Irenaeus was guided by the statement he found there. That statement in Papias itself is considered to be unfounded because the Gospel of Matthew was written in Greek and relied largely upon Mark, not the author's first-hand experience.
Herman N. Ridderbos writes (Matthew, p. 7):
This means, however, that we can no longer accept the traditional view of Matthew's authorship. At least two things forbid us to do so. First, the tradition maintains that Matthew authored an Aramaic writing, while the standpoint I have adopted does not allow us to regard our Greek text as a translation of an Aramaic original. Second, it is extremely doubtful that an eyewitness like the apostle Matthew would have made such extensive use of material as a comparison of the two Gospels indicates. Mark, after all, did not even belong to the circle of the apostles. Indeed Matthew's Gospel surpasses those of the other synoptic writers neither in vividness of presentation nor in detail, as we would expect in an eyewitness report, yet neither Mark nor Luke had been among those who had followed Jesus from the beginning of His public ministry.