Titanium only use 32 bit JDK in Windows.

Source URL: https://wiki.appcelerator.org/display/guides2/Installing+Oracle+JDK

Operating System	Min JDK Version	Max JDK Version	Package Arch Version	Download Location	Notes
Windows	6 (aka 1.6) rev 10	6 latest revision	32-bit only(x86 / i586)	Official Website	The 32-bit version of the JDK is required regardless of whether Titanium is running on a 32-bit or 64-bit Windows system. On Windows, Studio contains its own JRE, meaning you do not need to install the JDK before installing or launching Studio but will need it to use the Titanium SDK. Titanium Studio prompts you to install the JDK when installing the Android SDK from the Dashboard on Windows.
OS X	6 (aka 1.6) rev 10	6 latest revision	64-bit	Apple Developers	On Mac OS X 10.6 (Snow Leopard) and earlier, the JDK is preinstalled. On Mac OS X 10.7 (Lion) and later, the OS should prompt you to install it when needed.
Linux Desktop	6 (aka 1.6) rev 10	6 latest revision	32-bit and 64-bit	Official Website	This package must be installed to launch Studio on Linux systems. If using the 64-bit JDK, the ia32-libs package is required.