Swedish speakers in Finland are not immigrants anymore than Dutch speakers in Belgium are, though (the Dutch speaking area also generally does better than the French speaking areas, for a variety of reasons).
so clearly who does better has nothing to do with the language but with the economy and who has the better resources and is more adaptable to serve the current needs.
Saying language had no influence on who did better is inaccurate.
but what i meant to say is that language does not have an influence in an absolute sense in that say dutch speakers would always do better than french speakers or something like that because of the language somehow giving them an advantage. the advantage comes from being part of the group that is in power.