No, not really... in today's multiplexer example, the ``D'' input is supposed to be a logic input, i.e., its value is 0 or 1. In general you don't put non-logic levels into logic gates, or you won't get sensible results.
However the term ``multiplexer'' can refer to a more general circuit: it can mean any circuit for which multiple input lines are selected by an address. You can have a circuit with multiple analog input lines, such that the signal on only one line is sent through to an output (or processed in some way) if that line's address is set on some digital input line. However in this case the analog signals probably wouldn't be going directly into logic gates. They would be going into some ``front-end'' circuit that would handle them appropriately.