I was looking at the Noldor House of Finwë descendancy and on one side it shows Arwen, daughter of Elrond as we all know. But I didn't know this part: the other side breaks off into Aragorn as a descendant of Elros - Elrond's twin brother. Does that make them cousins?
Using the family-tree from http://lotrproject.com/, by my quick-count it seems Arwen and Aragorn II are first-cousins either 62 or 67 times removed, depending on whether you go through Aragorn's great x 14 grandfather (Arvedui) or great x 14 grandmother (Firiel) who both descended from Elendil (Arvedui on the Isildur side, Firiel on the Anarion side).
Hence Elendil is Aragorn's great x 38 grandfather as well as Aragorn's great x 43 grandfather.
The short answer is yes, they're directly related (first cousins) albeit separated by a very considerable age gap.
This handy family tree from The Encyclopaedia of Arda should be helpful to you:
Please note that the dotted line between Elros and Aragorn represents many thousands of years of lineage on Aragorn's side of the family.
Very distant first cousins, many many times removed.