Gerken kept his side in the game in the first half, saving superbly from Ryan Fraser, Eunan O'Kane and Lewis Grabban.
Daryl Murphy then put the away side ahead on 58 minutes, rifling a fine Frank Nouble cross past Lee Camp for his sixth goal of the season.
However, substitute Brett Pitman rescued a deserved point for the Cherries on 73 minutes, reacting quickly to finally beat Gerken after the keeper had made a superb save from Andrew Surman.
McCarthy, whose side are unbeaten in seven games, said: "Dean is terrific and has been a really good signing for us.
"It was a really good defensive performance in the end from everyone. We are delighted as we have just played a very good team.
"They have got good footballers and keep playing and passing it, Matt Ritchie is an outstanding footballer and Surman is terrific.
"We are on a good run and let's see if we can keep it going. Let's see where we can end up in May.
"I don't get caught up in the nonsense of talking about trying to win the league, let's just try and be as good as we can possibly can and then be realistic as to what we can achieve.
"All the stuff my lads do get you points and get you up the league and keep it competitive all the time. I like to be consistent."
After Pitman's fifth goal of the campaign Eddie Howe's men thought they had sneaked a winner four minutes later - but were controversially denied.
Ritchie's deep cross was turned into his own net by Gerken but referee Phil Gibbs ruled it out for a foul on the keeper by a stunned Tommy Elphick.
Pitman and Grabban both missed good chances late on as the home side failed to make it three wins in a row.
Cherries boss Eddie Howe said of the disallowed effort: "My initial reaction was I thought it was a goal.
"At first the referee was pointing to his hand but the only hand used was the keeper and they are allowed to use them.
"He has told the fourth official it was for a foul so I need to see it again.
"I felt we deserved three points and are disappointed we couldn't force a second goal. Credit to Ipswich for their defending but we are frustrated.
"Our performance was a really high level and I can't fault the players in any way. They are in really good form but we had great chances but didn't take them and at this level you need to take your opportunities."