Yeah, it's a huge advantage to host the world cup. But the thing is that the previous world cups have been usually held in countries in which they have a strong team to begin with, such as Brazil, Spain, Germany, England, Uruguay, and so on.
This is probably the first time that it's going to be held in a relatively weaker country. Maybe Korea-Japan 2002 could be comparable up to a point, and even then they managed to go past the first stage, which has been their all time best performance for both Korea and Japan.
We'll have to see if the boost for playing local is enough for Qatar.
I mentioned this previously. The Qatari national team has performed quite well in the recent few months, during the international friendlies and informal matches against various European club sides. And then during the world cup, they will be playing matches in their home ground, and that will give them an added advantage. But the first obstacle would be to get past the group stage. They are placed in a very tough group, alongside Netherlands, Ecuador and Senegal. And these three are very tough opponents.