Please check to see if my Spanish is correct?
Dudo que Gabriel (acordarse)____________ de mi numero de telefono.
Mama no me cree, pero es cierto que me (doler) _________ la garganta.
Cuando (ver) ____________ al camarero, llamalo.
Dudamos que Alberto (ser) _____________ tan amable como dices.
Es probable que se (dar-ellos) ___________ cuenta del mal olor que hay en la cocina.
Aunque (ser) ___________________ tarde, iremos al cine. (Indicate uncertainty)
No esta seguro de que su novia (estar) __________________ enojada.
Es posible que el camarero no (traer)______________ algo que no le pedimos.
?Cree Ud. que el vendedor (ser) __________ honrado? (Indicate a hint of doubt.)
Some of these sentences do not require subjunctive. The second one, for example, is indicative, as you have correctly written.
The third, however, should be subjunctive (tú form, because the command that follows is familiar).
I respectfully disagree with geofc on the last one. If it were worded differently ("No creo que...") it would call for subjunctive. You have done it correctly.
Remember that doubt calls for the subjunctive, so look over what you have done with those sentences.
In the third sentence, you are not the subject. "llámalo" is a command that you are giving someone else. Who?
Congratulations chica; you've provided answers.
Mostly you're good but for "Cuando (ver) ____________ al camarero, llamalo." Can't be "veo" because the speaker is asking you to call the waiter. So it should be "ves". Aunque (ser) ___________________ tarde, iremos al cine. (Indicate uncertainty) needs a subjunctive to indicate that uncertainty so "sea" not "es" ?Cree Ud. que el vendedor (ser) __________ honrado? (Indicate a hint of doubt.) needs to use the subjuctive for that hint of doubt. Hence you use "sea" not "es".
Bearing in mind that this is rather obviously an exercise in the subjunctive, you should trawl through the rest now to check if you need to change any more of them.