Christians, does result or numbers matter in evangelism? How do we measure the fruitfulness of our evangelism efforts?

That depends what 'evangel' you are trying to spread. If it's the message of the Jehovah's Witnesses, it absolutely does count - in their eyes - to spend as much time as you can stating their gospel message, and they expect results with people studying with you then coming along into "the organization". They want all their baptized members to recruit more baptized members. But if you share the good news about Jesus as detailed in the Bible, you simply obey Jesus' command to go into the world spreading the gospel, and baptisms will result with those whom the Holy Spirit converts. Nobody will check how much time you spend doing that or count any supposed 'results'.

Christians know that prophets like Jeremiah and Ezekiel had the daunting commission to warn the people even though nobody would listen to them. Today it's largely the same though, thank God, the Holy Spirit is still actively saving people through the gospel. It is still the Day of Salvation. But that will end as Jesus appears to start the Day of Judgment and Resurrection.

Obedience is what matters, not numbers saved. If that was the case, Noah would be deemed a failure, for his public witness didn't save a soul! Only his own family were saved! Jeremiah and Ezekiel would have failed their commission. But they didn't because they were obedient out of faith. Not out of a desire to accumulate supposed merit in God's eyes, or to save their own skins, as with those teaching a false gospel.

Evangelical practices make it very difficult to evaluate results. And it's not by accident. Compare with the results of the appearance of Mary/Our Lady of Guadalupe to Saint Juan Diego, in the year 1531, which shortly resulted in the (unlikely) conversion of over 9 million pagans, to Christ.   

Absolutely it does. Scripture goes out of its way to give us actual numbers of 'souls saved' by faith after hearing specific public addresses given by those speaking under inspiration of the Holy Spirit.

"And with many other words he solemnly testified and kept on exhorting them, saying, “Be saved from this perverse generation!”

"So then, those who had received his word were baptized; and that day there were added about three thousand souls." (Acts 2:40-41).

Those genuinely reached with the message of Christ will have an overwhelming desire to be publicly baptized, which is how we can recognize actual conversions. Until we are ready to 'own' our faith in public and endure any spiritual or physical persecution from society, we are not 'numbered among' Christ's Covenant members. That is why some Christians were even inspired in their conscience to be 'baptized for the dead' (1 Corinthians 15:29). 

Even after physical death, the desire to be publicly recognized with Christ can inspire the living to do it for them. That is how strong this impulse is and why GOD uses public baptism as the primary sign that true conversion has occurred.