Does the effect of naturalistic exposure on second language acquisition vary with age? A while back, I watched the movie The Terminal and the main character played by Tom Hanks learns to speak fluent English while he is stranded in the airport for more than a year. Which seems somewhat superfluous as I was of the opinion that picking up a new language when you grow older is not easy. But Tom Hanks' character manages to speak English quite fluently given his background. 

Dr Martha Young-Scholten of University of Newcastle mentions that the movie accurately describes how someone would acquire a second language under naturalistic exposure:


  Misrepresentations of complex issues such as adult second language (L2) acquisition are rife in the news media; one does not expect Hollywood to differ. Yet the 2004 film The Terminal (2004) gets it right. Stranded in a NY airport for a year, Tom Hanks’ character accurately depicts the early stages of acquisition and demonstrates how ample naturalistic exposure leads to advanced L2 proficiency. Hollywood also manages cultural nuances; initial communication fails because the authorities assume Hanks is attempting to immigrate when his purpose is one of pilgrimage.


If an individual is forced to use a language he is almost unfamiliar with, would it help him make significant progress in acquiring that language, regardless of his age?
(Unfortunately, the links appear to be broken, so I will reply to the title and bolded question.)

Being forced to use a language you are unfamiliar with as a language technique is known as immersion learning. I could not find direct comparisons of adults and children, but based on evidence from educational systems, it appears that early immersion does not change the helpfulness of immersion learning outcomes compared to late immersion, but interestingly, it does appear to change the way we obtain those learning outcomes (Harley and Hart, 1997).


  Evidence is found to support the main hypothesis that in late immersion starting in adolescence there will be a positive relationship between L2 [second language] outcomes and an analytical dimension of language aptitude, whereas in early immersion beginning in grade 1 a positive relationship will hold between L2 outcomes and memory ability. A further hypothesis that early immersion students will have higher language aptitude as a result of their early L2 exposure is not supported by the findings.


This would appear to at least partially satisfy the question. Since the question is about a fictional movie, I'll go out on a limb here and say that speculatively, an unrelated earlier study might be helpful in explaining why this could be the case. 

Newport (1990) reported support for the hypothesis that language learning abilities decline because of the expansion of nonlinguistic cognitive abilities. It's conceivable this allows individuals increasing freedom to avoid using second language, but these nonlinguistic abilities may be unhelpful in cases of extended immersion learning as depicted in The Terminal. 

References


Harley, B., &amp; Hart, D. (1997). Language aptitude and second language proficiency in classroom learners of different starting ages. Studies in second language acquisition, 19(03), 379-400.
Newport, E. L. (1990), Maturational Constraints on Language Learning. Cognitive Science, 14: 11–28. doi: 10.1207/s15516709cog1401_2