In general, it's not a good idea to use pattern matching (either Lua pattern or regex) to extract XML. Use a XML parser.
For this problem, you don't need to escape \
or <
(even if you do, Lua pattern uses %
to escape magic characters). And use brackets to get the node and its content:
data = string.match(Stream, "^.+(<TheNodeImLookingFor>.+</TheNodeImLookingFor>).+$")
Or to get only the content:
data = string.match(Stream, "^.+<TheNodeImLookingFor>(.+)</TheNodeImLookingFor>.+$")