A wanderer, if he's rich, is called a tourist.

Literal

Wanderer [topic-は], if-rich [conditional-ならば] tourist [quotative-と] be-called-[passive-称せられる]

Satirical observation. 放浪者 = wanderer, vagabond. 称する ('to be called, be named') is a formal Sino-Japanese synonym of 呼ぶ; its passive 称せられる = 'is called'. The conditional ~ならば (slightly literary, equivalent to ~なら) is embedded inside the topic. The wit lies in the contrast: same behavior, different label depending on wealth.