No, at least not beyond a certain point.

Entertainers increase guest happiness. Happiness is part of the rating, so entertainers do cause an increase. Most increases are capped, so you can only get so many points for happiness.

Lost guests lowers the rating directly. As I recall the lost guest penalty is uncapped. Blocking the entrance usually results in a park rating of 0 in the fullness of time, regardless of the park.

There are strange manipulations that allow guests to be trapped without the game realizing, which avoids the penalty. But as a normal player there's no action that overcomes the lost guest penalty.