Yes, I think that Carlos Latuff is a politically influential artist, because his cartoons reach so many people. With that wide of a following, it really does not matter how prolific or well-liked he is, because his cartoons reach so many people. He is controversial, so his statements have a great deal of influence.
Carlos Latuff produces political art in two ways. The first is in your face, but the second is less profound, and requires some thinking. The second involves art from the side, similar to what Andy Warhol did with Mao and Marylin Monroe. It can be more subjective, and opens up to what you think it is.
Carlos Latuff is from Brazil but is ethnically Lebanese. He is a political cartoonist who after visiting the middle east in the 1990's began publishing Anti-Zionist, Anti-Globalist, Anti-Capitalist, and Anti-U.S. Military interventionist cartoons. His cartoons are highly critical of Israeli's and portray Palestinians as being persecuted much like Jews in Nazi Germany, Blacks during South African Apartheid, and Tibetans in China. Latuff's cartoons are widely published in Arab websites with Anti Israeli and anti United States sentiment, so clearly his art is being used as a form of pro-palestinian propoganda.
There is no way to consider the art that Carlos Latuff creates as anything but politically driven. He is very much inspired by the Israeli and Palestinian conflict and the repercussions of the situation. I think that he is greatly influenced by these events and probably much more just like it.
Because I have never heard the name Carlos Latuff before in my life, and I have received a decent amount of fine arts education, I find it overwhelmingly unlikely that he is politically influential. In fact, I doubt his influence on any facet of society if his name is so easily unrecognized.