how many data records can i get while creating an API for a big data project ??!
What exactly is your question? If you use the streaming API, you are able to get quite a lot Tweets, but (as far as I know) if they exceed a specific number of Tweets per second or such, the Streaming API will not deliver you all Tweets but only a sample.
If you need to be absolutely sure to get all Tweet, you might want to look into firehose, and maybe Gnip, a company which provides Twitter data for i.e. analytics.