Can I pronounce a "t" as a glottal stop in the word "Netflix"
Solution 1:
In certain parts of America (but not all), you can use a glottal stop for a t in Netflix, as well as many double t's (kitten, button), terminal t's (but, net, fit, cat, pet, cot, bought). This will net you some strange looks in your travels, though. Being from New England originally, this was standard to my ear, but I had to change it as I moved around because of the unwanted attention it called to itself. If you can avoid it, it might to be to your benefit; those who use glottal stops will hardly notice it, and those who hear t's will find your English good.
Solution 2:
The specific environments in which /t/ can become [ʔ] in english varies slightly from dialect to dialect. At the beginnings of words /t/ almost always becomes [tʰ]. In dialects without [ʔ] or [ɾ], the sound almost always remains [t] anywhere else. Before a consonant or before a pause in speach, /t/ may become [ʔ]. However, in between vowels is more complicated. Some dialects will use [ɾ], while others use [ʔ]. This has lead to homophones between "latter" and "ladder" as /d/ can become [ɾ] in any environment other than at the start of a word.