Are you saying John 6:44 cancels 1 Corinthians 9? If so, you are horribly mistaking.
Here is your misunderstanding:
Paul winning souls and saving people points to Paul's work in the Kingdom. The Bible uses these words so we can't deny them. But this doesn't mean Paul apart from God. I think you want to remove Paul from the work because you have been working so hard without much result. I believe this is why you reject 1 Corinthians 9. But Paul saw winning souls (saving men) as his purpose - not because it was either Paul or God but because it was Christ in him and him in Christ.
This is why I can affirm both Jesus' words in John 6:44 AND Paul's words in 1 Corinthians 9. God is working through Paul, and God's Word does not come back void. It is also Paul's work in the Kingdom. I believe your denial of such human responsibility, because of your lack of visible confirmation, is why you deny 1 Corinthians 9. Such liberalism in interpretation is wrong, brother. 1 Corinthians 9 is just as much God's word as is John 6, and neither contradict the other.
1 Corinthians 9:18-24 (NASB)
What then is my reward? That, when I preach the gospel, I may offer the gospel without charge, so as not to make full use of my right in the gospel. For though I am free from all
men, I have made myself a slave to all,
so that I may win more. To the Jews I became as a Jew,
so that I might win Jews; to those who are under the Law, as under the Law though not being myself under the Law,
so that I might win those who are under the Law; to those who are without law, as without law, though not being without the law of God but under the law of Christ,
so that I might win those who are without law. To the weak I became weak,
that I might win the weak; I have become all things to all men,
so that I may by all means save some. I do all things for the sake of the gospel, so that I may become a fellow partaker of it. Do you not know that those who run in a race all run, but
only one receives the prize?
Run in such a way that you may win.
Don't look for excuses. Don't look to excuse yourself from the race. Run in such a way that you may win. This involves caring and ownership, not obeying how you want to obey and ignoring the result. It means putting your all into whatever God calls you to accomplish.