Minecraft does not start up and instead opens a blank game output tab in the launcher

Could you please have a look in the "Launcher Log" (2nd tab) and maybe copy its text in the description with "{code}" at the beginning and at the end?

It is normal that it opens a new tab called "Game Output". This contains later all the information about the game for example it logs commands you used, the chat etc. whereas the "Launcher Log" only logs the start of Minecraft and its components

Thank you for your report.
However, your ticket has been resolved as incomplete.

We are unable to diagnose your issue due to the lack of proper debug information. Please review the guidelines before reporting issues.
In case of a game crash, please also attach the crash log from [minecraft/crash-reports/crash-<DATE>-client.txt|http://hopper.minecraft.net/help/finding-minecraft-data-folder].

Reminder: For technical support please use the Mojang Support Center.

Sorry for the wait. Here's the launcher log.
http://pastebin.com/dR6pGhfG
I would just paste it, but it exceeds the character limit.

Caused by broken Java installation.
Download and install the Minecraft Installer from https://minecraft.net/download

I have reinstalled the minecraft launcher, but still am greeted with the same blank game output tab. Any other suggestions?

Again, I am sorry for the wait. The error shown is simply 'couldn't launch game' I managed to find the section of the log showing the error.

[18:06:21 ERROR]: Couldn't launch game
java.io.IOException: Cannot run program "C:\Program Files (x86)\Java\jre7\bin\javaw.exe" (in directory "C:\Users\Gianni\AppData\Roaming\.minecraft"): CreateProcess error=2, The system cannot find the file specified
	at java.lang.ProcessBuilder.start(Unknown Source) ~[?:1.8.0_40]
	at com.mojang.launcher.game.process.direct.DirectGameProcessFactory.startGame(DirectGameProcessFactory.java:14) ~[launcher.jar:1.6.11]
	at net.minecraft.launcher.game.MinecraftGameRunner.launchGame(MinecraftGameRunner.java:208) [launcher.jar:1.6.11]
	at com.mojang.launcher.game.runner.AbstractGameRunner.onDownloadJobFinished(AbstractGameRunner.java:186) [launcher.jar:1.6.11]
	at com.mojang.launcher.updater.download.DownloadJob.popAndDownload(DownloadJob.java:122) [launcher.jar:1.6.11]
	at com.mojang.launcher.updater.download.DownloadJob.access$000(DownloadJob.java:12) [launcher.jar:1.6.11]
	at com.mojang.launcher.updater.download.DownloadJob$1.run(DownloadJob.java:86) [launcher.jar:1.6.11]
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_40]
	at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_40]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.8.0_40]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.8.0_40]
	at java.lang.Thread.run(Unknown Source) [?:1.8.0_40]
Caused by: java.io.IOException: CreateProcess error=2, The system cannot find the file specified
	at java.lang.ProcessImpl.create(Native Method) ~[?:1.8.0_40]
	at java.lang.ProcessImpl.<init>(Unknown Source) ~[?:1.8.0_40]
	at java.lang.ProcessImpl.start(Unknown Source) ~[?:1.8.0_40]

Click "Edit Profile" and uncheck the Executable box.

It works now! Thanks for the help!

I'm having the same issue, I have unchecked the Executable box and it isn't working.

This is what I am seeing in "GameOutPut"

"[21:05:17] [Client thread/INFO]: Setting user: DameonFear
[21:05:17] [Client thread/INFO]: (Session ID is token:c4a4a81bccb1454aad38b1fe5bd4a331:1daa1099618a4a57b87c380b9c84f688)
Exception in thread "Client thread" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1
at com.google.gson.Gson.fromJson(Gson.java:815)
at com.google.gson.Gson.fromJson(Gson.java:768)
at lu.b(SourceFile:151)
at lu.<init>(SourceFile:43)
at net.minecraft.server.MinecraftServer.<init>(SourceFile:155)
at bpp.<init>(SourceFile:41)
at avf.<init>(SourceFile:293)
at net.minecraft.client.main.Main.main(SourceFile:124)
Caused by: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was STRING at line 1 column 1
at com.google.gson.stream.JsonReader.beginArray(JsonReader.java:338)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:79)
at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
at com.google.gson.Gson.fromJson(Gson.java:803)
... 7 more
Java HotSpot(TM) 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release"

What should I do?

@Justin, that's a different issue. See MC-75309. It's typically fixed by doing a clean install of the game.