I read somewhere that 'mainatges' means 'children' in the dialect of Toulosse. Is it an occitan word? Do you use it also in french? And how is the "tg" pronounced? Is it similar to the sound on 'bridge' in english?
Yes, it is an Occitan word, cognate with French ménage, related to the word maison "house". Mainatge could be used in regional French by people who happen to be familiar with the Occitan word. For example, there is a folk music group in the Aude called "Les Maïnatges de Montréal".
The ‹tg› is usually pronounced like Spanish ‹ch›, although in some dialects it is still voiced (as in Catalan mainatge). You can hear someone pronouncing the Occitan word here: mainatge.