The Greek here is clear: poor in Spirit. It is not talking here of the financially/physically poor (Though there are many other places in the Bible that certainly point to the fact that God has a special place in his heart for those who are poor! Some commentators also make mention of the parallels bet. the two and how the primary audience would have seen them as synonymous in many ways). He is saying that the people who are poor in spirit--those who recognize their deep spiritual need for God. It's those who are so self-aware that they realize that even at their best, they need God's continued grace and presence in their lives.

Notice that the two Gospel writers Matthew and Luke have different emphases--> Matthew's emphasis is that of the "poor in spirit" and Luke's is the "poor." So we may say with confidence that God's blessing rests on those who are humbled spiritually AS WELL AS those who are humbled physically and materially.

Matthew 5:3