If a person wants to receive the gift of the Holy Ghost, they must repent first.

"And the apostles and brethren that were in Judaea heard that the Gentiles had also received the word of God." - Acts 11:1 KJV     

Peter went up to Jerusalem to testify of how he wound up going to a Gentile’s home and preaching the gospel to them.

"But Peter rehearsed the matter from the beginning, and expounded it by order unto them…" - Acts 11:4 KJV     See these verses: Acts 11:5-14

"And as I began to speak, the Holy Ghost fell on them, as on us at the beginning." - Acts 11:15 KJV (Acts 2:4)

The Holy Ghost fell on the Gentiles just as it fell on the Jews on the Day of Pentecost in the upper room. (Acts 2:4)

"And they of the circumcision [the Jews] which believed were astonished, as many as came with Peter, because that on the Gentiles also was poured out the gift of the Holy Ghost. For they heard them speak with tongues, and magnify God…" - Acts 10:45-46 KJV

"Forasmuch then as God gave them the like gift as he did unto us, who believed on the Lord Jesus Christ; what was I, that I could withstand God?

When Peter heard the Gentiles speaking in tongues as the Spirit gave them utterance he knew they had received the gift of the Holy Ghost. However, they had received the gift without entering the covenant with Jesus by baptism in Jesus name.

"Then answered Peter, Can any man forbid water, that these should not be baptized, which have received the Holy Ghost as well as we? And he commanded them to be baptized in the name of the Lord." - Acts 10:46-48 KJV

Peter told the brethren in Jerusalem all that happened.

“When they heard these things, they held their peace, and glorified God, saying, Then hath God also to the Gentiles granted repentance unto life." - Acts 11:18 KJV

How did the brethren in Jerusalem know that the Gentiles Peter preached to had repented?

They knew this because God does not fill a person with His Spirit unless they have repented first.

Repentance is necessary before receiving the gift of the Holy Ghost as well as before getting water baptized in Jesus name.  A person must crucify his carnal nature first.

"And when he had called the people unto him with his disciples also, he said unto them, Whosoever will come after me, let him deny himself, and take up his cross, and follow me. For whosoever will save his life shall lose it; but whosoever shall lose his life for my sake and the gospel's, the same shall save it." - Mark 8:34-35 KJV

Jesus died for our sins, was buried, and rose on the third day to life. (The Gospel - the death, burial, and resurrection of Jesus 1 Corinthians 15:1-4.) 

We OBEY the Gospel by repentance (becoming dead to sin), baptism in JESUS name (buried with Him by baptism), and receiving His Holy Ghost (resurrection to New Life in Jesus). (Romans 6:1-13).

We must crucify our sinful nature BEFORE we can be buried in baptism OR resurrected to walk in newness of Life. Jesus will not fill us with His Spirit unless we repent first.

Because of this, if a person receives the Holy Ghost speaking in tongues (as the Gentiles did in Acts 10), then that person has repented.