Hi Dave,Shannon, there was no fixed number. Titanic was approved to carry up to 3,547 passengers and crew. However, some of the accommodation at the aft end of G deck was removable and could be varied. Also, some of the beds were doubles, so there's no straight answer.
The approved maximum number was split into
905 First Class.
564 Second Class.
1134 Third Class
In practice, it was unlikely that such numbers would ever be carried.