“I” is emphatic, distinguishing Jesus from all others.

“you do not accept me” = Robertson, among others, calls John “the Gospel of the Rejection” (RWP) #John 1:11; 3:11,32; 12:37

Joh 1:11  He came to that which was his own, but his own did not receive him.

Joh 3:11  I tell you the truth, we speak of what we know, and we testify to what we have seen, but still you people do not accept our testimony.

Joh 3:32  He testifies to what he has seen and heard, but no-one accepts his testimony.

Joh 12:37  Even after Jesus had done all these miraculous signs in their presence, they still would not believe in him.

“you will accept him” = Jesus is saying that they will not receive the true Christ who comes in the name of the Father, but they will receive (and already have) those who falsely claim to be the Christ. McGarvey states that, “According to Schudt, as quoted by Bengel, there have been 64 antichrists who have misled the Jews. Among them Bar Cocheba (c. AD 132) led 24,000 to ruin, including Akiba, the President of the Sanhedrin. False christs come in their own name—for their own honor—and make no war on bosom sins, but upon earthly enemies; but Jesus came not to manifest himself, but his Father.” (TFG 208)