"Them" from the context of the story are Cornelius and his Gentile contacts. However, Peter does not call them Gentiles in his account to the Jewish believers at Jerusalem.
## the same gift ##
Peter is referring to the gift of the Holy Spirit.
## who was I, that I could oppose God? ##
I could not oppose God (See: [[rc://en/ta/man/translate/figs-rquestion]])
## when they heard these things ##
<b>when they heard these things <b>- "they", the circumcision group who were criticizing Peter.