Is then sensible to think that language may have a link with GDP. The following graph shows the GDP per capita by language. The data was gathered from IMF, World Bank and CIA.
The first languages (most spoken) of each country were alloted with 80% of the countries´ population and the second language the remaining 20%. Although that can´t be true for all countries I found it a good estimate globally. I couldn't find a more detailed information.
The graph only shows languages with more than a million speakers.
English is in the middle of the graph because many poor countries in Africa speak English and the same happens with French