By that sort of logic anything and everything you can imagine is real and anything and everything can get to our universe at any time for any reason with any consequence to it's arrival.
Heres the flaw in the logic:
a) There is an infinite number of universes: sure lets accept this.
b) There exists at least 1 santa clause: sure lets accept this. There is infinite universes so therefore what we consider a santa clause could be a roach in another universe.
c) There must exist at least 1 S.C. which can travel between universes and into ours. Lets assume this is not true. Why? Because we have yet to prove that such a thing is currently possible. Lets move away from proving. There are two possibilities here:
Possibility a: It is possible to travel between universes at any time. Which means that by probability there will be at least one santa that wants to travel to our univese to our plannet at this exact time.
Possibility b: It is impossible to travel between universes, and to keep it simple, to our current time and location. Which means that given infinite iterations, the chance that santa is coming this year is zero.
A or B, the rest is faith. In any case I tend to believe B otherwise I am waiting on my unicorn damnit!
TGJ: To disprove you:
a) Santa can store items in his sack which may be actually stored in a way which does not take up 3 dimentional space.
b) Santa might be a roach (see comments above) so he just needs to visit 24 times for a few minutes with his entire immediate family.
c) It is also possible that santa actually take a VERY long time to delivery gifts one at a time. He travels to each house individually and leaves, at which point he time travels to the exact moment of arrival at the previous house, thus he delivers ALL gives simultaneously.