my female dog has tied 6times with our male, can I say that chances are she is now pregnant?

Not necessarily. 

We have two males and one female the female is 2yrs the males are 3yrs and 10mths, it is the 10mth who has mated her and tied 6 times, the older male once, they are not related, wish I knew if it was a success, although we have 2 males they all get on brilliant, no fighting or aggro,

I'm sorry but are you really saying that you have no idea which of these dogs could be the sire of any puppies and that you allowed a 10 month old PUPPY to mate with your bitch? Are you completely irresponsible? Did you read any of the threads on here about responsible breeding? I daresay you didn't bother with any health screening either? I sincerely hope that either this is a wind up or if not that your bitch is not pregnant because it is people like you who give dog breeders a bad name.

You might want to look up the requirements for health testing here and then start hoping that there are NO puppies on the way.

I strongly recommend a trip to the vet and get the Alizen injection for your bitch - 2 injections, 48 hours apart, and no puppies.

If this isn't a wind-up, then this is just about the most irresponsible way to produce a litter of puppies, and you're leaving yourself wide open for legal action if any puppies result and they prove to be unhealthy.

Take the bitch to the vet for the mismate injection and keep her ell away from your males for the next two or three weeks.

I can't believe this, letting both males at the same female is bad enough but the over use of a male this young could seriously damage him.

The males may get on till now but they are now competing for the female and you can't go back on that.

Then there are all the health tests that should have been done before any breeding takes place.

The mis mate injection should be given to prevent any pups.

Let's hope its a joke.