All right, so the language module in your brain needs correct sentences. But how many sentences do you actually need to become fluent in a language?
First of all, the question is a bit misleading, because there isn't a single answer for all situations. The number of sentences you need will depend on many factors:
•the difficulty of the sentences (e.g. if you get too easy or too difficult sentences, you won't learn much)
•the style of the sentences (if you read too much literary language, it will not help you speak)
•your pace (if you get more sentences per day, you need fewer sentences in total, because you forget less information)
•how you get the sentences and how much attention you pay to them (when reading, it is possible to analyze each sentence much more carefully, so you can get more information out of each sentence, but you also read more slowly)
•your innate skills (some people need more input before they can speak, others "get it" very quickly)
•how close your first language is to the language you are learning (a speaker of Dutch needs much less input to learn English than a speaker of Japanese)
How much input did I get? It took me about 3 years to get from basic English skills to fluency. During those 3 years, I was exposed to about 1,000,000 English sentences (not necessarily different sentences). About 400,000 of these were written sentences (books, SuperMemo reviews, dictionaries, classroom reading); 600,000 were spoken sentences (TV, recordings, listening to teachers, listening to my American cousin, classroom listening).
Note that these are very rough estimates. The actual number of sentences that I got during that 3-year period may well have been 700,000 or 1,500,000.
I know. One million is a big number. But when you break it down, it looks far less scary:
So if you want to follow in my footsteps, you'll have to get about 60 pages of written English and 6 hours of spoken English per week — for three years. (I am assuming you already have some basic English skills that enable you to understand this article. If you are a total beginner, you will have to get to that level first.) If you think 60 pages and 6 hours is a lot, consider the following points:
•Using an English-English dictionary with example sentences and SuperMemo reviews take care of perhaps 15 pages of written English per week. This leaves 45 pages per week for traditional reading (websites, books).
•Reading 45 pages per week may seem scary when you are just beginning to read in English. But I promise you — you will be devouring English texts in no time!
•Remember that things like listening to your teacher, having conversations in English, watching videos on YouTube, watching House M.D., playing Mass Effect, etc. all count as "listening time". (This does not mean that 6 hours of playing a videogame fulfills the 6-hour requirement — you need 6 hours of talking without breaks, as in an interview.)