Fantastic question!
"First the argument fails to show any correlation between people viewing television program on visual art and people visiting art museums." --- to be fair, this is not quite true. The argument shows one very specific numerical correlation. However, I see what you mean. Indeed, as both sarb and kuttingchai correctly pointed out, we don't know if the increase in TV viewership and the increase in museum attendance are related - although the fact that both increased by 15% is something to think about. satb, another small correction: "Secondly the author assumes that the same group of people participated in the two polls." --- no, this was not an assumption.
However, let's assume that two are related. Let's assume that those are the same people who are going to the museums and watching visual arts on TV. In my personal opinion, it would be almost insane to assume that they are going to the museums because of watching TV. In my personal opinion, it is much more likely to be the other way round: people first start going to the museums and then later come to watch visual art on TV. Perhaps, those are just educated people interested in the culture. If visual arts program are removed from TV, it is likely to increase museum attendance rather than decrease - or, perhaps, people would just watch visual arts programs on the web.
I also like the point about corporate funding. sarb mentioned that this reduced funding may or may not decrease the number of programs on visual arts, whereas kuttingchai made a different point, noticing that this reduced funding may or may not decrease the attendance at the museums because commercials may still be shown. However, there is more to be said. First of all, we are not even sure that the funding will be reduced, it is only being threatened. Then, even if it will be reduced, and even if it will reduce the audience at the museums, it is not at all clear that some funds should be reallocated to public television. Why not directly to the museums or to the development of visual art websites in the Internet?
In fact, I do not even see why the funds should be reallocated at all. Decreased attendance at the museums is something we can live with. If indeed those were the people who came because of TV commercials and do not have much appreciation for the museums otherwise, fine. Let's not force them into attending museums. Perhaps, this is not their cup of tea. Of course, it may be argued that museums would lose some profits without these TV programs. Even if this is the case, investing city's funds supporting arts into TV programs with the purpose of making profit from the city's museums is not necessarily a wise solution. If the objective is to generate profit, then there should be wiser ways to invest.
kuttingchai, "Also, author should provide statistical evidence on how reduction in corporate funding that supports visual arts television program will negatively impact the attendance at city's art museum." --- a small correction. There cannot be statistical evidence on something that has not yet happened ("...will negatively affect..."). Statistical evidence is only available for past events, not for the future. Statistical evidence can only help us to predict the effect of the reduction on the museum's attendance.
I think kuttingchai's response is a little bit stronger. This response makes it more clear that the issue is the connection between the programs shown on TV and the attendance at the museums. sarb's response is similar, but a little less clear, including some typos and some unfinished sentences. The last sentence could be more polished: "Without using such information the argument makes a hasty suggestion regarding city funds." The expression "using such information" is wordy and unclear. Also, "hasty" suggestion is a judgment, possibly unjustified.
Both responses demonstrate critical thinking and can be improved by incorporating stronger critical thinking. For example, instead of just mentioning that correlation between TV program viewership and museum attendance does not imply causation, it is also possible to consider causation in the opposite direction: perhaps, people watch visual arts on TV after or because they attend museums. It is also always good to keep the big picture in mind: just because the attendance at the museums decreased does not mean that there is necessarily a problem to fix. Even if we are to fix the problem (of the decreasing attendance at the museums), we do not have to fix it in the same way as before. New ways of attracting people to museums may be appropriate including, but not limited to, creating quality content for the Internet.