The whole society in Europe is affected by a few key leaders, and the Pope is one of those huge influences. The fact that this is one of the most progressive and caring pope's in modern times and the fact that he has spoken up for the poor and disenfranchised has had to have an influence on treatment of the Roma.
Yes, a Pope's positive treatment of Roma influences the rest of Europe on the matter, because the Pope is the most noted Catholic in the world. When the Pope speaks, people listen. He is treated like a rock star. The Pope's word is golden. He can do a great deal of good in instructing the European people to integrate the Roma.
In Lutheran countries, who usually don't care about anyone who isn't Germanic or Jewish, they will not feel the desire to treat Roma the right way. Besides only Catholics listen to the pope, so only Catholic countries will take action to help the Roma people. So yeah there you have it.
A Pope's positive treatment of Roma does not influence the rest of Europe on the matter. This is because the church's role is to remind people about Christian forgiveness and acceptance. The issue goes far beyond these things for those who live in the community with the Roma. When they see their resources being used up and a high level of thievery, there anger comes out and is justified.
A Pope is to be commended for positive treatment of the Roma people, but I do not think his actions will influence the rest of Europe. Europe has resented and looked down on the Roma for hundreds of years. They consider them the very bottom rung on the human ladder and treat them as such. Europeans feelings toward the Roma people have been too long ingrained to be easily changed.
The Pope does not really have a lot of sway over issues and opinions, and the new Pope might have the least. Pope Francis is great - and he's doing the right thing for the Catholic Church - but he's made PR mistakes by over saturating the media with too many things for people to really focus on.