If you are taking accuracy to mean 'taking what the Iliad says', then yes.

The Iliad gives, in the famous 'ship list', a list of how many ships each king/ruler provides and in many cases how many men. Even ancient Greeks themselves tried to work out how large the total force was as a result- the 5th century Athenian Thucydides tried to use an average number for the ships with unnamed numbers of occupants, though he never gives his actual estimate. However, he counts 1200 total ships mentioned as part of the Greek expedition (the precise number the text mentions is 1186 by my count, but what's a few warships between friends?). When taking the Iliad's description of the ships and their men, the minimum guess for the size of the expedition he's talking about is 100,000 men.

So if anything, the movie Troy is at times smaller scale than the number of men and ships that the Iliad implies.

However, if you take accuracy to mean 'likely happened', then we're kind of stumped. A lot of work has been done to try to understand what polities and institutions existed in Mycenaean era Greece, the consensus still being (to my understanding) that a kingdom based out of Mycenae had hegemonic control over most of what we would now call Greece. This was an era of large cities and palatial complexes, and organised states, so it wouldn't be impossible to imagine the population being large enough to raise that many armed followers and retainers. The issue is more that this is a very large size for an army in almost any era, and it's very hard to imagine that this army actually staying in the area around Troy for 10 years. Sure, the Iliad and other works allude to the Greeks besieging and taking several other minor cities tributary to Troy in the meantime, but the implication is still that the main body of the army was sat on the beaches besieging the Trojans directly.

But that gets us into wider questions of 'is the Iliad representing the bare bones of an essentially true story, or is it an essentially fictional story with some truthful bits added'. The issue of evaluating what, if any, parts of the Iliad are accurate for real events is an enormous one and too wide to get into.

What this boils down to is- if 'realistic' refers to what the Iliad says, then yes Troy is realistic. If it means 'was likely what happened and was feasible', we don't really have a way of answering that yet.