This is an active question in much of the United States and North Dakota right now. The answer is elusive and this recent post on FocusEconomics by Oliver Wright makes that abundantly clear.
One of the major issues making this difficult to determine is the sheer volume of variables to consider. Again, the FocusEconomics blog post does a great job of laying these out: from the pace of integration of the refugees, the age structure differences between the immigrants and the current population, the labor force needs and so on.
The time frame under consideration is important as well. Short run and long run outcomes could be quite different based on many of the factors mentioned already. Immigrants, refugees or otherwise, make contributions to economies, the question is the net gain, and the timing of the gains. There are likely no universal answers about this; it will vary by country, time period, and other issues but can be an important complement to the human issues in such a situation.
