Weather or not it prevents ketosis will depend on if you eat enough of it that your body no longer needs to make its own glucose.
If you provide enough of a dietary source for glucose, ketosis will stop.
It always comes down to quantity taken in over a given time period as well as how insulin sensitive you.
Probably the more important part is how insulin sensitive you are. Some people can get 5-10g dietary carbohydrate and though it may not technically be enough to provide all your body's glucose needs for that next few hours, it may start up a cycle of insulin overreaction which prompts your liver to secrete glycogen to prevent blood sugar going low. Your liver may overreact and provide too much glycogen resulting in more insulin and there the cycle goes for hours preventing ketosis. This is how insulin resistance works against weight loss.
So the answer to your question is that it varies widely from person to person.