Notice in verse 45, it is termed "the gift of the Holy Spirit." The word "also" indicates the same "baptism" with the Holy Spirit as Peter and the apostles had received. So that was extend to the Gentiles as well.
In Acts 11:15-17, it is plainly described as the same "baptism" with the Holy Spirit that the apostles had received. Now these had received the "baptism" with the Spirit, is the way it is worded there in Acts 11.
True, at Cornelius' house they did receive the "baptism" with the Spirit, and thereby were baptized by the Spirit into the church before water baptism—but Peter immediately commanded water baptism. This was a rare exception to the rule.
But there is no promise that anyone will receive the Holy Spirit until baptized in water—even though God in His wisdom and love may on rare occasions make an exception. The command is, "Repent, and be baptized"—and then, "you shall receive the gift of the Holy Spirit."
