Boring Answer: We don't know until Infinity War II Comes out

Presumably included in the futures Dr. Strange saw is the one where he tells Quill about Gamora ahead of time. Maybe your question (and the countless of similar ones we are all coming up with) will be addressed in the movie, but there's probably no way to account for all of them.

Of course, since Dr. Strange told Tony as he was disappearing that This was the only way, we have to presume that the one unique winning future hadn't been ruled out by that moment, meaning Quill's actions didn't damn the universe.

Better Answers

Part of the fun of addressing alleged plot holes in movies is coming up with counter-examples for them, right? So let's have fun and throw some options out:

1. Quill wouldn't have been able to contain himself during the fight

Maybe Dr. Strange saw every possible future where an attempt was made to get an informed Quill to contain his emotions, but in each scenario the fight was lost.

2. Thanos couldn't have been defeated without Quill

Dr. Strange couldn't just take out Quill (e.g., infinite falling a la Loki in Ragnarok) ahead of time because the tide of the battle would have turned to Thanos' favor without Quill's contributions.

3. Maybe Thanos needed to almost lose the gauntlet in order for future events to transpire

Thanos was within about a second of losing everything he had worked for. Maybe in that moment, as happens cinematically with a near-death experience, his life choices had been flashed in front of him. Maybe the recollection of that will influence his choices in the next film.

4. Maybe defeating Thanos on the spot would have been certain doom in other ways

I know it's perverse to think of our Avengers this way, but maybe Dr. Strange saw the futures where the gauntlet does come off and land on the ground in all sorts of ways. Subsequently, mere sight and reach of unimaginable power corrupts one, or several, or all of the present Avengers (looking at the rabbit in particular, here). Maybe one of them grabs it and does terrible things. Or maybe none of them do and the gems get put in some "safe place" that is eventually raided and a worse outcome than the Thanos one happens. I mean, really, in the MCU where are you going to safely stash the gauntlet that someone won't come looking for it?

Or something else? We will be in a better place to answer questions about Dr. Strange's decision after the next (and hopefully last) Infinity War movie comes out. Until then, hopefully the above suggestions are enough to ease your mind that there are possibilities that the writers didn't just botch this whole thing.

While Dr. Strange had seen all possible outcomes, there is no way for him to know exactly which future was happening while they were planning. There is nothing to suggest that while there is only 1 successful future out of 14 million, that they have actual control of making this happen (though they will try).

The more he sees things unfold with the Thanos battle on Titan, and as more information is presented, he can narrow down the number of possible futures that are taking place. By the time he gives the time stone to Thanos, he has enough information to know the best possible action to make the successful outcome possible.

I think it's reasonable to assume that Dr. Strange can only recollect the single winning outcome after viewing the possible futures. Further, I expect he would focus solely on the key decisions of this win (i.e., what made it a win), and simply forgot inconsequential details (i.e., what doesn't meaningfully change the outcome), and the details of the remaining millions of losses in possible futures.

In Avengers: Endgame, Dr. Strange...

...appears surprised when a dam bursts in the final battle, which he has to resolve, making him unable to participate in the remainder of the final fight.

This is consistent with Dr. Strange not committing the entirety of the single winning future to memory, just the key decisions that lead to the win.

If Dr. Strange would have told Quill about Gamora, then we should expect either:

1. the Avengers lose (e.g., because the conflict is important to the final outcome: If Dr Strange knew the outcome why did he put up the fight?), where Dr. Strange would need to deliberately withhold this information, or
2. the Avengers still win in essentially the same way, where Dr. Strange may not have committed Gamora's death to memory.

Either way, Thanos inevitably gets the infinity stones.

One uncomplicated storyline which may thus happen if Dr. Strange mentions Gamora's death to Quill is:

Thanos loses his gauntlet, but fights and gets it back moments later.

Resulting in either no meaningful changes, or the Avengers losing.

I contend this is plausible judging from Avengers: Endgame where...

Thanos is a strong match for the Avengers even without a single infinity stone, and almost achieves another snap by snatching Tony Stark's infinity-stone gauntlet.