What do you mean you have a Tmobile card? You mean a Tmo sim card?
Anyways OTA update means over the provider's cell network. A Tmobile hotspot is simply wifi, which is just the plain ol' internet. If I assume you mean you have a Tmo sim card, and an active account, which is a given or you wont get on their network, then you could get the update. But no, using a device from one provider on another provider's network means you are on your own as for support for the device.
Of course I nor anyone else I know on this forum works at Tmo, so just give them a call to find out.