Jesus would be with billions on earth if He was on earth. Eventually He may get around to meeting personally, everyone many times over eternity. In an orthodox Christian sense, which seems also to be a Biblical sense to me, Jesus dwells with and in all Christians, as in passages like this one:
John 14:23
Jesus replied, “If anyone loves Me, he will keep My word. My Father will love him, and We will come to him and make Our home with him.
This means that the Spirit of God (being the same as the Spirit of Christ, because there is only one Spirit Eph 4:4-6) is in all Christians, as the "anyone" in John 14:23 indicates, and so all Christians are born again in this way.
If Jesus says the thief will be with Jesus in paradise then I believe it.
I suppose with the JW teachings some plain things in scripture have to be ignored or got around somehow and this is one of them. Others may be that the great crowd are seen before the throne in Revelations and in JW teachings this cannot be in heaven and so has to be got around. The New Jerusalem is said to be coming down out of heaven (Rev 3:12........... the new Jerusalem, which is coming down out of heaven from my God; ....) God and the Lamb are said to be in that New Jerusalem and God is said to come and dwell with His people and to dwell in Zion/Jerusalem forever. The OT saints are said to be in the New Jerusalem with all people of faith it seems:
Heb 11:8 By faith Abraham, when called to go to a place he would later receive as his inheritance, obeyed and went, even though he did not know where he was going. 9 By faith he made his home in the promised land like a stranger in a foreign country; he lived in tents, as did Isaac and Jacob, who were heirs with him of the same promise. 10 For he was looking forward to the city with foundations, whose architect and builder is God. 11 And by faith even Sarah, who was past childbearing age, was enabled to bear children because she considered him faithful who had made the promise. 12 And so from this one man, and he as good as dead, came
descendants as numerous as the stars in the sky and as countless as the sand on the seashore.
And I could go on with examples like this in other topics also.
The JW Bible interpretation seems to be based on the Watchtower teachings rather than the teachings based on the Bible in many cases.
The thief being with Jesus in paradise but not being with Him seems to be just another example.
When it comes to the actual placement of the coma in the passage (Luke 23:43) it is true that Jesus said many times, "truly I say to you" but never "truly I say to you today" unless the JW teachings about Luke 23:43 are correct, in which case Jesus said it once.
This seems to be a case of interpreting and translating the Bible according to the Watchtower teachings.