How did they know that he had gone in? Neither Brewer, Postal, or Burroughs saw anyone go in at that time, and Brewer and Burroughs did not see him when they checked the balcony and the theater area.
Brewer sees Saint Patsy acting suspiciously. Brewer decides to keep an eye on Saint Patsy. Brewer watches Saint Patsy walk in the direction of the TT. Brewer sees Saint Patsy reach the front of the theater and disappear.
Brewer isn't standing directly in front of the theater so I guess it's accurate that 55 years later a troll could state Brewer didn't see Saint Patsy enter the theater.
It's also accurate for the troll to state Brewer doesn't initially see Saint Patsy in the balcony or ground floor seating of the darkened theater.
Unfortunately for the troll, once the lights in the theater go on, Brewer most definitely does see the man that was acting strangely in front of his store - the same man that he trailed and watched walk to the front of the theater and disappear.
That man's name was Lee Harvey Oswald, AKA Saint Patsy.
Trolletti will continue to ask 'how do we know he entered the theater', not because the answer isn't obvious, but because that's what TROLLS do.